Is Lean sustainable in today's NHS hospitals? A systematic literature review using the meta-narrative and integrative methods

Is Lean sustainable in today's NHS hospitals? A systematic literature review using the... Abstract Purpose Methodological variance and quality, heterogeneity of value and divergent approaches are reasons for the varied results of Lean interventions in healthcare despite ongoing global popularity. However, there is piecemeal evidence addressing the sustainability of initiatives—the aim of this review is to use an integrative approach to consider Lean’s sustainability and the quality of available evidence in today’s National Health Service (NHS). Data sources A literature review of AMED, CINAHL, Cochrane, JBI, SCOPUS, DelphiS, MEDLINE, EMBASE, MIDIRS, Web of Science and PsycINFO electronic databases was conducted. Study selection Peer-reviewed studies in NHS hospitals/trusts that concerned undiluted, service-wide Lean adoption and contained quantitative data were included. Reference lists were consulted for evidence via a snowball approach. Methodological quality was assessed using an adapted critical appraisal tool. Data extraction Research design, method of intervention, outcome measures and sustainability were extracted. Results of data synthesis Electronic searches identified 12 studies eligible for inclusion. This comprised of five quasi-experimental designs (one mixed-method), three multi-site analyses, one action research, one failure mode and effects analysis, one content analysis of annual reports and one systematic review. Six articles considered sustainability with two of these providing measured successes. Despite diverse and positive outcomes studies lacked scientific rigour, failed to consider confounding issues, were at risk of positive bias and did not demonstrate sustainability with any statistical significance. Conclusion Lean has ostensible value but it is difficult to draw a conclusion on efficacy or sustainability. Higher quality scientific research into Lean and the effect of staffing cultures on initiatives are needed to ascertain the extent that Lean can affect healthcare quality and subsequently be sustained. quality measurement, quality management, quality improvement, quality management, leadership, quality management, quality culture, quality management, audit, external quality assessment Introduction There has been increasing movement in recent years to improve the quality of care provided by the National Health Service (NHS) alongside pressure for growth in efficiency and reduction in costs. Governmental and NHS policies, documents and reports have addressed this directly, suggesting various quality improvement (QI) methodologies [1–4]. The last 20 years have also seen growth in productivity in the NHS stagnating in comparison with the UK economy [3] generating widespread call to create whole-scale and disruptive change to the current health sector status quo [3–5]. To address the crisis in funding and efficiency [5], the NHS has turned to a number of QI ideologies, often originally described or discovered outside the health sector [6]. The methodology used by automotive manufacturer Toyota has gathered specific attention—a 5-year study from the Massachussetts Institute of Technology coined these processes as ‘Lean’ [7]. Lean is defined as a continuous QI methodology intended to remove waste, create efficiency and improve safety from the perspective of the end-user. Toyota’s success was cited and measured by the reduction in defects and factory floor space, savings in costs and worker satisfaction—a change in working culture and not necessarily new tools and equipment [8]. The paradigm of Lean is to evaluate the process or production flow (termed ‘value stream’) and identify areas where waste is being created prior to eliminating it [9]. Lean has become a global management phenomenon having been applied to health-sectors internationally [10]. Transparency in its values and broad applicability means Lean has often been simplified for healthcare adoption [11]; methods such as the 5 S’s (sort, set in order, shine, standardise and sustain) have been used and applied to a range of settings [12]. Inherent in Lean is the Japanese notion of ‘kaizen’ which refers to continuous QI—rechecking processes and making adjustments. Kaizen is necessary for Lean to be sustainable, however, ensuring it occurs within the framework of organisational change can be difficult [13]. Lean’s efficacy is promoted in a number of healthcare areas, but there is little evidence directly addressing its sustainability in broad health service adoption [14]. Over the last decade, the NHS has introduced Lean methodology tentatively as a suggestion [15, 16], more firmly in policy [17, 18] and a nationwide initiative [19] with a view to addressing the necessary changes. This has been with conflicting or ambiguous supporting evidence where both diluted [15] and undiluted implementations have been promoted as necessary by the same author [4, 15, 19]. Yet, this is not reflected in the cited evidence [20] where undiluted and system-wide adoption is deemed more beneficial. Despite lack of systematic evidence supporting efficacy, the NHS introduced ‘The Productive Ward: Releasing Time to Care’ [19] (referred to in this study as PW—the trademarked package, not generic terms or interventions) nationwide in 2007. The program of modules was widely adopted [19] and supported [21] then later sold internationally [22]. PW remains in its infancy, with no clear evidence-based conclusion over its efficacy despite global uptake [23, 24]. In 2014, the Department of Health went on to incorporate Lean methodology into national health policy. ‘The new era of thinking and practice in change and transformation: A call to action for leaders of health and care’ [4] asserts that Lean is tried, tested and proven to be successful [4]. However, contemporaneous systematic evidence suggests there is positive publication bias in PW [23] that direct application of Lean to healthcare is suboptimal [6] and that there continues to be a gap between theory and practice [25]. The national policy, written by the one of the authors of PW, states that it is ‘time for heresy’ [4: p.22] and calls for whole-scale, disruptive change to healthcare, specifically promoting Lean to achieve this [4]. However, there is continued debate and uncertainty around Lean’s overall efficacy [26], its applicability to practice [27], manner of adoption [28] and sustainability [29]. Infancy in its development compared with its sector of origin [30] is cited as contributory to this. There also remains agreement that the quality and nature of evidence is mixed [31] or poor [32], continuously evolving and not finite [33]. However, manner of adaptation to practice and the recipient practice culture are paramount to success [34, 35]. There is also a central issue—that research into large-scale transformational change in complex organisations is problematic—there is little referential evidence [36] alongside a lack of a universal scale for measuring Lean, making appraisal of its efficacy and sustainability difficult [37]. However, the ostensible view of Lean in the NHS is one of positivity: wide adoption [19], uptake [23] and the genesis of profitable international commoditisation [38]; Lean has been promoted as a necessary panacea [39]. The intention of this study is to address this gap in knowledge [25] with reference to sustainability, in particular, the dearth of sustained results of implementations [14] alongside a tendency for studies to mention, but not explicitly address sustainability [26]. Methods An integrative literature review incorporates mixed-designs and theoretical literature alongside controlled study designs to provide comprehensive analysis; it is an important tool to improve the science and practice of healthcare and gives a rounded view of a complex intervention [40]. This study adopts an integrative approach as outlined by Torraco [41] alongside a meta-narrative approach to literature review as suggested by Greenhalgh et al. [42]. Data sources Comprehensive searches were conducted of the following electronic databases: AMED, CINAHL, Cochrane Database, DelphiS, EMBASE, JBI Database, MEDLINE, MIDIRS, PsycINFO, SCOPUS and Web of Science. The keywords ‘lean’, ‘productiv*’, ‘releasing time’ and also ‘time to care’ were entered to conduct the searches. Various Boolean (AND/OR) operators were applied in order to increase the size of search results. There was no restriction on year of publication although filters were applied for peer-reviewed, published literature in combination with a geographical filter for studies in the UK. Only articles published in the English Language were included. Study selection This process has been mapped in Fig. 1. In order to be included in the study, an article had to satisfy the following criteria: primary or secondary peer-reviewed literature that focuses on a clear (undiluted) Lean intervention where there is measurement of the intervention itself. The study must be evaluating the whole adoption over an aspect of Lean redesign. The broad criteria allowed a variety of sources to become eligible for consideration whilst simultaneously excluding news reports, small case or individual studies/stories that lacked depth of data field/academic rigour. Defining the Lean intervention as undiluted reduced the risk of inherent confounding and adhered to the theoretical basis of Lean needing to be a whole-scale and cultural adoption [20]. There was no restriction on the date of publication in the knowledge that this was self-limiting owing to the recent boom in interest in Lean healthcare [35]. Figure 1 View largeDownload slide PRISMA [43] flow diagram. Figure 1 View largeDownload slide PRISMA [43] flow diagram. The identification of articles included in this review was completed in four stages: (i) the initial search results of 5127 articles were examined to remove anything duplicate or deemed irrelevant. A reduced list of 101 articles was then subject to the (ii) snowball approach where reference lists were scanned and 44 additional references were gleamed. (iii) Further duplicate removal, and inspection of abstracts then occurred and a short-list of 32 articles was compiled. These were then subject to (iv) a full-text, methodological review where the size of the presented data field was inspected; validated critical appraisal tools (AMSTAR [44] and CASP [45]) were used to verify decisions with regard to inclusion; this process provided the final 12 studies for inclusion—see Table 1. Table 1 Detailed list of literature eligible for inclusion in the review Title  Author(s)  Year  Journal  Setting  Intervention  Method  Outcome  Limitations  New development: using lean techniques to reduce radiology waiting times  Lodge A and Bamford D  2008  Public Money and Management  The division of diagnostics and clinical support—Pennine Acute Hospital Trust. 2000 staff and 150 medical consultants.  Value-stream mapping —construction of an intranet-based waiting list.  Action research: (quasi-experimental—interrupted time) study of the division of diagnostics and clinical support.  Reduction in modal waiting times of 25–50% in different departments.  No statement of limitations or ethical consideration. Internal validity: no awareness of confounding despite clear potential for confounding (new technology).  Application of lean principles can reduce inpatient prescription dispensing times  Beard J and Wood D  2010  The Pharmaceutical Journal  Pharmacy Department of Musgrove Hospital, Taunton and Somerset NHS Trust—Inpatient Dispensary.  Process and value mapping and failure mode effect of current processes. PDCA.  Failure mode effects analysis; continuous re-evaluation of the process. Aspects of interrupted time series.  Median dispensing times reduced from 188 min to 27 min (SD 7 min). Error rates unchanged.  Bias: observers were aware of the hypothesis. There was a lack of control to the study—no comparative group (aside from baseline working). Possibility of confounding (Hawthorne)  Effect of a ‘Lean’ intervention to improve safety processes and outcomes on a surgical emergency unit  McCulloch P, Kreckler S, New S, Yezen S, Handa A, and Catchpole K  2010  BMJ  Emergency General Surgery Ward—John Radcliffe Hospital (38 beds)  Targeting five of the seven care processes relevant to patient safety incorporating The five S’s Process Mapping Error Visibility Elimination of Waste PDCA  Quasi-experimental interrupted time series study of 38 bed units where 969 patients were admitted before intervention, 1114 admitted after intervention was implemented.  Patients requiring ward admission fell 27–20%. Adverse events were unchanged (factors felt to be external to intervention)  No clear randomisation or blinding in samples for study. Observers were aware of hypothesis.  Lean thinking: can it improve the outcome of fracture neck of femur patients in a district general hospital?  Yousri TA, Khan Z, Chakrabarti D, Fernandes R, and Wahab K  2011  Injury  Fracture neck of femur patients at Goodhope Hospital (NHS).  Value-stream approach was applied to patients admitted—identification and elimination of waste.  Quasi-experimental interrupted time series: 608 patients in total were recruited—309 pre-lean, 299 post-intervention.  Statistically significant reduction in 30 days (5%) and overall (9.3%) mortality. Reduction in door to theatre times, bed usage and increase in early discharge.  No statement of limitation or ethical consideration. Internal validity: no awareness of confounding. Risk of bias from observers.  Implementing lean in healthcare: making the link between the approach, readiness and sustainability  Radnor Z  2011  International Journal of Industrial Engineering and Management  Two NHS acute hospitals and one NHS mental health trust.  Various interventions across each provider—included ‘rapid improvement events’, value-stream mapping and PW-based initiatives.  Mixed-method secondary research of a range of data from the interventions. Analysis of three case studies consisting of 55 interviews and 13 focus groups.  Suggests a model or framework for further lean implementation and comments on the sustainability of each intervention.  Bias risk—Recruitment to study: three large and useful case studies but no systematic approach to recruitment—no clear statement of rationale for this. No ethical consideration.  The adoption, local implementation and assimilation into routine nursing practice of a national quality improvement programme: The Productive Ward in England  Robert G, Morrow E, Maben J, Griffiths P, and Callard L  2011  Journal of Clinical Nursing  Routine data, online survey of 150 respondents and 58 interviews across five organisations.  Analysis of PW—secondary research not individual intervention or case-control.  Mixed-method secondary research (analysis of routine data, online survey, interviews).  Provides outcomes for a range of interventions in a range of settings.  Bias risk—recruitment to study; no systematic approach. Research funded by NHSI (creator of PW). Broad, unspecific issue. No inclusion of ‘control’ or failure groups for comparison.  Implementing large-scale quality improvement: lessons from The Productive Ward: Releasing Time to Care.  Morrow E, Robert G, Maben J, and Griffiths P  2012  International Journal of Health Care Quality Assurance  Large-scale research across a number of organisations in the NHS.  Range of methods implemented across the various environments—largely ‘productive ward/releasing time to care’.  Mixed-method 15 semi-structured interviews of national-level policy-makers, 150 surveys of senior managers, five hospital case studies involving 58 staff.  Implementation was widely supported but various facilitators and challenges were identified.  Bias risk—recruitment to study. Funded by NHSI (creator of PW). Large and non-specific goal/aim of study. No ethical consideration. Recruitment strategy non-randomised and unclear.  One-stop cholecystectomy clinic: an application of lean thinking—can it improve the outcomes?  Siddique K, Effat S, Elsayed A, Cheema R, Mirza S, and Basu S  2012  Journal of Perioperative Practice  General Surgery Department, William Harvey Hospital, Kent. DGH of 550 beds serving 300 000 people.  A ‘one-stop’ surgical intervention where the patient undergoes the preoperative assessment and surgery in the same visit.  Interrupted time series quasi-experimental. About 141 medical records reviewed, 12 excluded. This cohort was compared with a routine cohort.  Number of hospital visits and preoperative admissions lower in one-stop patients. Waiting times were reduced.  No consideration of confounding or Hawthorne effect. Non-controlled method, no randomisation. Observer bias. No awareness of limitations.  Evaluating Lean in healthcare  Burgess N and Radnor Z  2013  International Journal of Healthcare Quality Assurance  Analysis of a number of English hospitals (NHS).  Various interventions employed by a large number of organisations nationally.  Lean implementation snapshots: content analysis of all annual reports and websites over two time periods.  Divergent approaches to Lean interventions identified. Implementation tends to be isolated rather than system-wide.  Bias risk—recruitment to study strategy unclear. Nature of study design is questionable to achieve stated aims. Results of study are unclear. No ethical considerations.  A mixed model study evaluating lean in the transformation of an Orthopaedic Radiology service  Martin AJ, Hogg P, and Mackay S  2013  Radiography  Radiology Department of Royal Bolton Hospital (NHS).  Value-stream identification and implementation.  Mixed-method analysis of qualitative and quantitative outcomes prior to and post-lean intervention. Questionnaires of both patients and staff.  About 50% and 60% reductions in pathway lengths, 60–69% reduction in patient waiting times. Better quality of patient and staff experience post-intervention. Improvement in patient waiting times.  No acknowledgement of confounding—new service with new technology. Significantly larger amount of respondents post-intervention. Unclear results of study. No ethical considerations. Observer bias.  A systematic literature review of Releasing Time to Care: the Productive Ward  Wright S and McSherry W  2013  Journal of Clinical Nursing  Review of literature across a number of settings.  A number of interventions applied across the different areas of research.  Systematic review of 18 articles identified following a comprehensive literature search.  Safety improvement and reduction of infection. Potential positive publication/results bias. Benefit to patients, frontline staff and cost-savings.  No ethical consideration of cited papers. No acknowledgement of limitations of study.  Improving the service for patients receiving extracorporeal photopheresis using Lean principles  Rushton C, Robertson L, Taylor T, Taylor P, Button P, and Alfred A  2016  British Journal of Nursing  A photopheresis unit, Rotherham NHS Foundation Trust.  Value-stream mapping and identification/elimination of waste, patient scheduling and service structure redesign.  Interrupted time series of 55 patients receiving 140 treatments over a 1-month period. ‘Kaizen’ event 2 months’ post-intervention to measure quality.  Delay in arrival to start of treatment improved 47%. No change to wait for assessment or treatment.  Potential for confounding. Observer bias. No randomisation, lack of controlled design.  Title  Author(s)  Year  Journal  Setting  Intervention  Method  Outcome  Limitations  New development: using lean techniques to reduce radiology waiting times  Lodge A and Bamford D  2008  Public Money and Management  The division of diagnostics and clinical support—Pennine Acute Hospital Trust. 2000 staff and 150 medical consultants.  Value-stream mapping —construction of an intranet-based waiting list.  Action research: (quasi-experimental—interrupted time) study of the division of diagnostics and clinical support.  Reduction in modal waiting times of 25–50% in different departments.  No statement of limitations or ethical consideration. Internal validity: no awareness of confounding despite clear potential for confounding (new technology).  Application of lean principles can reduce inpatient prescription dispensing times  Beard J and Wood D  2010  The Pharmaceutical Journal  Pharmacy Department of Musgrove Hospital, Taunton and Somerset NHS Trust—Inpatient Dispensary.  Process and value mapping and failure mode effect of current processes. PDCA.  Failure mode effects analysis; continuous re-evaluation of the process. Aspects of interrupted time series.  Median dispensing times reduced from 188 min to 27 min (SD 7 min). Error rates unchanged.  Bias: observers were aware of the hypothesis. There was a lack of control to the study—no comparative group (aside from baseline working). Possibility of confounding (Hawthorne)  Effect of a ‘Lean’ intervention to improve safety processes and outcomes on a surgical emergency unit  McCulloch P, Kreckler S, New S, Yezen S, Handa A, and Catchpole K  2010  BMJ  Emergency General Surgery Ward—John Radcliffe Hospital (38 beds)  Targeting five of the seven care processes relevant to patient safety incorporating The five S’s Process Mapping Error Visibility Elimination of Waste PDCA  Quasi-experimental interrupted time series study of 38 bed units where 969 patients were admitted before intervention, 1114 admitted after intervention was implemented.  Patients requiring ward admission fell 27–20%. Adverse events were unchanged (factors felt to be external to intervention)  No clear randomisation or blinding in samples for study. Observers were aware of hypothesis.  Lean thinking: can it improve the outcome of fracture neck of femur patients in a district general hospital?  Yousri TA, Khan Z, Chakrabarti D, Fernandes R, and Wahab K  2011  Injury  Fracture neck of femur patients at Goodhope Hospital (NHS).  Value-stream approach was applied to patients admitted—identification and elimination of waste.  Quasi-experimental interrupted time series: 608 patients in total were recruited—309 pre-lean, 299 post-intervention.  Statistically significant reduction in 30 days (5%) and overall (9.3%) mortality. Reduction in door to theatre times, bed usage and increase in early discharge.  No statement of limitation or ethical consideration. Internal validity: no awareness of confounding. Risk of bias from observers.  Implementing lean in healthcare: making the link between the approach, readiness and sustainability  Radnor Z  2011  International Journal of Industrial Engineering and Management  Two NHS acute hospitals and one NHS mental health trust.  Various interventions across each provider—included ‘rapid improvement events’, value-stream mapping and PW-based initiatives.  Mixed-method secondary research of a range of data from the interventions. Analysis of three case studies consisting of 55 interviews and 13 focus groups.  Suggests a model or framework for further lean implementation and comments on the sustainability of each intervention.  Bias risk—Recruitment to study: three large and useful case studies but no systematic approach to recruitment—no clear statement of rationale for this. No ethical consideration.  The adoption, local implementation and assimilation into routine nursing practice of a national quality improvement programme: The Productive Ward in England  Robert G, Morrow E, Maben J, Griffiths P, and Callard L  2011  Journal of Clinical Nursing  Routine data, online survey of 150 respondents and 58 interviews across five organisations.  Analysis of PW—secondary research not individual intervention or case-control.  Mixed-method secondary research (analysis of routine data, online survey, interviews).  Provides outcomes for a range of interventions in a range of settings.  Bias risk—recruitment to study; no systematic approach. Research funded by NHSI (creator of PW). Broad, unspecific issue. No inclusion of ‘control’ or failure groups for comparison.  Implementing large-scale quality improvement: lessons from The Productive Ward: Releasing Time to Care.  Morrow E, Robert G, Maben J, and Griffiths P  2012  International Journal of Health Care Quality Assurance  Large-scale research across a number of organisations in the NHS.  Range of methods implemented across the various environments—largely ‘productive ward/releasing time to care’.  Mixed-method 15 semi-structured interviews of national-level policy-makers, 150 surveys of senior managers, five hospital case studies involving 58 staff.  Implementation was widely supported but various facilitators and challenges were identified.  Bias risk—recruitment to study. Funded by NHSI (creator of PW). Large and non-specific goal/aim of study. No ethical consideration. Recruitment strategy non-randomised and unclear.  One-stop cholecystectomy clinic: an application of lean thinking—can it improve the outcomes?  Siddique K, Effat S, Elsayed A, Cheema R, Mirza S, and Basu S  2012  Journal of Perioperative Practice  General Surgery Department, William Harvey Hospital, Kent. DGH of 550 beds serving 300 000 people.  A ‘one-stop’ surgical intervention where the patient undergoes the preoperative assessment and surgery in the same visit.  Interrupted time series quasi-experimental. About 141 medical records reviewed, 12 excluded. This cohort was compared with a routine cohort.  Number of hospital visits and preoperative admissions lower in one-stop patients. Waiting times were reduced.  No consideration of confounding or Hawthorne effect. Non-controlled method, no randomisation. Observer bias. No awareness of limitations.  Evaluating Lean in healthcare  Burgess N and Radnor Z  2013  International Journal of Healthcare Quality Assurance  Analysis of a number of English hospitals (NHS).  Various interventions employed by a large number of organisations nationally.  Lean implementation snapshots: content analysis of all annual reports and websites over two time periods.  Divergent approaches to Lean interventions identified. Implementation tends to be isolated rather than system-wide.  Bias risk—recruitment to study strategy unclear. Nature of study design is questionable to achieve stated aims. Results of study are unclear. No ethical considerations.  A mixed model study evaluating lean in the transformation of an Orthopaedic Radiology service  Martin AJ, Hogg P, and Mackay S  2013  Radiography  Radiology Department of Royal Bolton Hospital (NHS).  Value-stream identification and implementation.  Mixed-method analysis of qualitative and quantitative outcomes prior to and post-lean intervention. Questionnaires of both patients and staff.  About 50% and 60% reductions in pathway lengths, 60–69% reduction in patient waiting times. Better quality of patient and staff experience post-intervention. Improvement in patient waiting times.  No acknowledgement of confounding—new service with new technology. Significantly larger amount of respondents post-intervention. Unclear results of study. No ethical considerations. Observer bias.  A systematic literature review of Releasing Time to Care: the Productive Ward  Wright S and McSherry W  2013  Journal of Clinical Nursing  Review of literature across a number of settings.  A number of interventions applied across the different areas of research.  Systematic review of 18 articles identified following a comprehensive literature search.  Safety improvement and reduction of infection. Potential positive publication/results bias. Benefit to patients, frontline staff and cost-savings.  No ethical consideration of cited papers. No acknowledgement of limitations of study.  Improving the service for patients receiving extracorporeal photopheresis using Lean principles  Rushton C, Robertson L, Taylor T, Taylor P, Button P, and Alfred A  2016  British Journal of Nursing  A photopheresis unit, Rotherham NHS Foundation Trust.  Value-stream mapping and identification/elimination of waste, patient scheduling and service structure redesign.  Interrupted time series of 55 patients receiving 140 treatments over a 1-month period. ‘Kaizen’ event 2 months’ post-intervention to measure quality.  Delay in arrival to start of treatment improved 47%. No change to wait for assessment or treatment.  Potential for confounding. Observer bias. No randomisation, lack of controlled design.  Table 1 Detailed list of literature eligible for inclusion in the review Title  Author(s)  Year  Journal  Setting  Intervention  Method  Outcome  Limitations  New development: using lean techniques to reduce radiology waiting times  Lodge A and Bamford D  2008  Public Money and Management  The division of diagnostics and clinical support—Pennine Acute Hospital Trust. 2000 staff and 150 medical consultants.  Value-stream mapping —construction of an intranet-based waiting list.  Action research: (quasi-experimental—interrupted time) study of the division of diagnostics and clinical support.  Reduction in modal waiting times of 25–50% in different departments.  No statement of limitations or ethical consideration. Internal validity: no awareness of confounding despite clear potential for confounding (new technology).  Application of lean principles can reduce inpatient prescription dispensing times  Beard J and Wood D  2010  The Pharmaceutical Journal  Pharmacy Department of Musgrove Hospital, Taunton and Somerset NHS Trust—Inpatient Dispensary.  Process and value mapping and failure mode effect of current processes. PDCA.  Failure mode effects analysis; continuous re-evaluation of the process. Aspects of interrupted time series.  Median dispensing times reduced from 188 min to 27 min (SD 7 min). Error rates unchanged.  Bias: observers were aware of the hypothesis. There was a lack of control to the study—no comparative group (aside from baseline working). Possibility of confounding (Hawthorne)  Effect of a ‘Lean’ intervention to improve safety processes and outcomes on a surgical emergency unit  McCulloch P, Kreckler S, New S, Yezen S, Handa A, and Catchpole K  2010  BMJ  Emergency General Surgery Ward—John Radcliffe Hospital (38 beds)  Targeting five of the seven care processes relevant to patient safety incorporating The five S’s Process Mapping Error Visibility Elimination of Waste PDCA  Quasi-experimental interrupted time series study of 38 bed units where 969 patients were admitted before intervention, 1114 admitted after intervention was implemented.  Patients requiring ward admission fell 27–20%. Adverse events were unchanged (factors felt to be external to intervention)  No clear randomisation or blinding in samples for study. Observers were aware of hypothesis.  Lean thinking: can it improve the outcome of fracture neck of femur patients in a district general hospital?  Yousri TA, Khan Z, Chakrabarti D, Fernandes R, and Wahab K  2011  Injury  Fracture neck of femur patients at Goodhope Hospital (NHS).  Value-stream approach was applied to patients admitted—identification and elimination of waste.  Quasi-experimental interrupted time series: 608 patients in total were recruited—309 pre-lean, 299 post-intervention.  Statistically significant reduction in 30 days (5%) and overall (9.3%) mortality. Reduction in door to theatre times, bed usage and increase in early discharge.  No statement of limitation or ethical consideration. Internal validity: no awareness of confounding. Risk of bias from observers.  Implementing lean in healthcare: making the link between the approach, readiness and sustainability  Radnor Z  2011  International Journal of Industrial Engineering and Management  Two NHS acute hospitals and one NHS mental health trust.  Various interventions across each provider—included ‘rapid improvement events’, value-stream mapping and PW-based initiatives.  Mixed-method secondary research of a range of data from the interventions. Analysis of three case studies consisting of 55 interviews and 13 focus groups.  Suggests a model or framework for further lean implementation and comments on the sustainability of each intervention.  Bias risk—Recruitment to study: three large and useful case studies but no systematic approach to recruitment—no clear statement of rationale for this. No ethical consideration.  The adoption, local implementation and assimilation into routine nursing practice of a national quality improvement programme: The Productive Ward in England  Robert G, Morrow E, Maben J, Griffiths P, and Callard L  2011  Journal of Clinical Nursing  Routine data, online survey of 150 respondents and 58 interviews across five organisations.  Analysis of PW—secondary research not individual intervention or case-control.  Mixed-method secondary research (analysis of routine data, online survey, interviews).  Provides outcomes for a range of interventions in a range of settings.  Bias risk—recruitment to study; no systematic approach. Research funded by NHSI (creator of PW). Broad, unspecific issue. No inclusion of ‘control’ or failure groups for comparison.  Implementing large-scale quality improvement: lessons from The Productive Ward: Releasing Time to Care.  Morrow E, Robert G, Maben J, and Griffiths P  2012  International Journal of Health Care Quality Assurance  Large-scale research across a number of organisations in the NHS.  Range of methods implemented across the various environments—largely ‘productive ward/releasing time to care’.  Mixed-method 15 semi-structured interviews of national-level policy-makers, 150 surveys of senior managers, five hospital case studies involving 58 staff.  Implementation was widely supported but various facilitators and challenges were identified.  Bias risk—recruitment to study. Funded by NHSI (creator of PW). Large and non-specific goal/aim of study. No ethical consideration. Recruitment strategy non-randomised and unclear.  One-stop cholecystectomy clinic: an application of lean thinking—can it improve the outcomes?  Siddique K, Effat S, Elsayed A, Cheema R, Mirza S, and Basu S  2012  Journal of Perioperative Practice  General Surgery Department, William Harvey Hospital, Kent. DGH of 550 beds serving 300 000 people.  A ‘one-stop’ surgical intervention where the patient undergoes the preoperative assessment and surgery in the same visit.  Interrupted time series quasi-experimental. About 141 medical records reviewed, 12 excluded. This cohort was compared with a routine cohort.  Number of hospital visits and preoperative admissions lower in one-stop patients. Waiting times were reduced.  No consideration of confounding or Hawthorne effect. Non-controlled method, no randomisation. Observer bias. No awareness of limitations.  Evaluating Lean in healthcare  Burgess N and Radnor Z  2013  International Journal of Healthcare Quality Assurance  Analysis of a number of English hospitals (NHS).  Various interventions employed by a large number of organisations nationally.  Lean implementation snapshots: content analysis of all annual reports and websites over two time periods.  Divergent approaches to Lean interventions identified. Implementation tends to be isolated rather than system-wide.  Bias risk—recruitment to study strategy unclear. Nature of study design is questionable to achieve stated aims. Results of study are unclear. No ethical considerations.  A mixed model study evaluating lean in the transformation of an Orthopaedic Radiology service  Martin AJ, Hogg P, and Mackay S  2013  Radiography  Radiology Department of Royal Bolton Hospital (NHS).  Value-stream identification and implementation.  Mixed-method analysis of qualitative and quantitative outcomes prior to and post-lean intervention. Questionnaires of both patients and staff.  About 50% and 60% reductions in pathway lengths, 60–69% reduction in patient waiting times. Better quality of patient and staff experience post-intervention. Improvement in patient waiting times.  No acknowledgement of confounding—new service with new technology. Significantly larger amount of respondents post-intervention. Unclear results of study. No ethical considerations. Observer bias.  A systematic literature review of Releasing Time to Care: the Productive Ward  Wright S and McSherry W  2013  Journal of Clinical Nursing  Review of literature across a number of settings.  A number of interventions applied across the different areas of research.  Systematic review of 18 articles identified following a comprehensive literature search.  Safety improvement and reduction of infection. Potential positive publication/results bias. Benefit to patients, frontline staff and cost-savings.  No ethical consideration of cited papers. No acknowledgement of limitations of study.  Improving the service for patients receiving extracorporeal photopheresis using Lean principles  Rushton C, Robertson L, Taylor T, Taylor P, Button P, and Alfred A  2016  British Journal of Nursing  A photopheresis unit, Rotherham NHS Foundation Trust.  Value-stream mapping and identification/elimination of waste, patient scheduling and service structure redesign.  Interrupted time series of 55 patients receiving 140 treatments over a 1-month period. ‘Kaizen’ event 2 months’ post-intervention to measure quality.  Delay in arrival to start of treatment improved 47%. No change to wait for assessment or treatment.  Potential for confounding. Observer bias. No randomisation, lack of controlled design.  Title  Author(s)  Year  Journal  Setting  Intervention  Method  Outcome  Limitations  New development: using lean techniques to reduce radiology waiting times  Lodge A and Bamford D  2008  Public Money and Management  The division of diagnostics and clinical support—Pennine Acute Hospital Trust. 2000 staff and 150 medical consultants.  Value-stream mapping —construction of an intranet-based waiting list.  Action research: (quasi-experimental—interrupted time) study of the division of diagnostics and clinical support.  Reduction in modal waiting times of 25–50% in different departments.  No statement of limitations or ethical consideration. Internal validity: no awareness of confounding despite clear potential for confounding (new technology).  Application of lean principles can reduce inpatient prescription dispensing times  Beard J and Wood D  2010  The Pharmaceutical Journal  Pharmacy Department of Musgrove Hospital, Taunton and Somerset NHS Trust—Inpatient Dispensary.  Process and value mapping and failure mode effect of current processes. PDCA.  Failure mode effects analysis; continuous re-evaluation of the process. Aspects of interrupted time series.  Median dispensing times reduced from 188 min to 27 min (SD 7 min). Error rates unchanged.  Bias: observers were aware of the hypothesis. There was a lack of control to the study—no comparative group (aside from baseline working). Possibility of confounding (Hawthorne)  Effect of a ‘Lean’ intervention to improve safety processes and outcomes on a surgical emergency unit  McCulloch P, Kreckler S, New S, Yezen S, Handa A, and Catchpole K  2010  BMJ  Emergency General Surgery Ward—John Radcliffe Hospital (38 beds)  Targeting five of the seven care processes relevant to patient safety incorporating The five S’s Process Mapping Error Visibility Elimination of Waste PDCA  Quasi-experimental interrupted time series study of 38 bed units where 969 patients were admitted before intervention, 1114 admitted after intervention was implemented.  Patients requiring ward admission fell 27–20%. Adverse events were unchanged (factors felt to be external to intervention)  No clear randomisation or blinding in samples for study. Observers were aware of hypothesis.  Lean thinking: can it improve the outcome of fracture neck of femur patients in a district general hospital?  Yousri TA, Khan Z, Chakrabarti D, Fernandes R, and Wahab K  2011  Injury  Fracture neck of femur patients at Goodhope Hospital (NHS).  Value-stream approach was applied to patients admitted—identification and elimination of waste.  Quasi-experimental interrupted time series: 608 patients in total were recruited—309 pre-lean, 299 post-intervention.  Statistically significant reduction in 30 days (5%) and overall (9.3%) mortality. Reduction in door to theatre times, bed usage and increase in early discharge.  No statement of limitation or ethical consideration. Internal validity: no awareness of confounding. Risk of bias from observers.  Implementing lean in healthcare: making the link between the approach, readiness and sustainability  Radnor Z  2011  International Journal of Industrial Engineering and Management  Two NHS acute hospitals and one NHS mental health trust.  Various interventions across each provider—included ‘rapid improvement events’, value-stream mapping and PW-based initiatives.  Mixed-method secondary research of a range of data from the interventions. Analysis of three case studies consisting of 55 interviews and 13 focus groups.  Suggests a model or framework for further lean implementation and comments on the sustainability of each intervention.  Bias risk—Recruitment to study: three large and useful case studies but no systematic approach to recruitment—no clear statement of rationale for this. No ethical consideration.  The adoption, local implementation and assimilation into routine nursing practice of a national quality improvement programme: The Productive Ward in England  Robert G, Morrow E, Maben J, Griffiths P, and Callard L  2011  Journal of Clinical Nursing  Routine data, online survey of 150 respondents and 58 interviews across five organisations.  Analysis of PW—secondary research not individual intervention or case-control.  Mixed-method secondary research (analysis of routine data, online survey, interviews).  Provides outcomes for a range of interventions in a range of settings.  Bias risk—recruitment to study; no systematic approach. Research funded by NHSI (creator of PW). Broad, unspecific issue. No inclusion of ‘control’ or failure groups for comparison.  Implementing large-scale quality improvement: lessons from The Productive Ward: Releasing Time to Care.  Morrow E, Robert G, Maben J, and Griffiths P  2012  International Journal of Health Care Quality Assurance  Large-scale research across a number of organisations in the NHS.  Range of methods implemented across the various environments—largely ‘productive ward/releasing time to care’.  Mixed-method 15 semi-structured interviews of national-level policy-makers, 150 surveys of senior managers, five hospital case studies involving 58 staff.  Implementation was widely supported but various facilitators and challenges were identified.  Bias risk—recruitment to study. Funded by NHSI (creator of PW). Large and non-specific goal/aim of study. No ethical consideration. Recruitment strategy non-randomised and unclear.  One-stop cholecystectomy clinic: an application of lean thinking—can it improve the outcomes?  Siddique K, Effat S, Elsayed A, Cheema R, Mirza S, and Basu S  2012  Journal of Perioperative Practice  General Surgery Department, William Harvey Hospital, Kent. DGH of 550 beds serving 300 000 people.  A ‘one-stop’ surgical intervention where the patient undergoes the preoperative assessment and surgery in the same visit.  Interrupted time series quasi-experimental. About 141 medical records reviewed, 12 excluded. This cohort was compared with a routine cohort.  Number of hospital visits and preoperative admissions lower in one-stop patients. Waiting times were reduced.  No consideration of confounding or Hawthorne effect. Non-controlled method, no randomisation. Observer bias. No awareness of limitations.  Evaluating Lean in healthcare  Burgess N and Radnor Z  2013  International Journal of Healthcare Quality Assurance  Analysis of a number of English hospitals (NHS).  Various interventions employed by a large number of organisations nationally.  Lean implementation snapshots: content analysis of all annual reports and websites over two time periods.  Divergent approaches to Lean interventions identified. Implementation tends to be isolated rather than system-wide.  Bias risk—recruitment to study strategy unclear. Nature of study design is questionable to achieve stated aims. Results of study are unclear. No ethical considerations.  A mixed model study evaluating lean in the transformation of an Orthopaedic Radiology service  Martin AJ, Hogg P, and Mackay S  2013  Radiography  Radiology Department of Royal Bolton Hospital (NHS).  Value-stream identification and implementation.  Mixed-method analysis of qualitative and quantitative outcomes prior to and post-lean intervention. Questionnaires of both patients and staff.  About 50% and 60% reductions in pathway lengths, 60–69% reduction in patient waiting times. Better quality of patient and staff experience post-intervention. Improvement in patient waiting times.  No acknowledgement of confounding—new service with new technology. Significantly larger amount of respondents post-intervention. Unclear results of study. No ethical considerations. Observer bias.  A systematic literature review of Releasing Time to Care: the Productive Ward  Wright S and McSherry W  2013  Journal of Clinical Nursing  Review of literature across a number of settings.  A number of interventions applied across the different areas of research.  Systematic review of 18 articles identified following a comprehensive literature search.  Safety improvement and reduction of infection. Potential positive publication/results bias. Benefit to patients, frontline staff and cost-savings.  No ethical consideration of cited papers. No acknowledgement of limitations of study.  Improving the service for patients receiving extracorporeal photopheresis using Lean principles  Rushton C, Robertson L, Taylor T, Taylor P, Button P, and Alfred A  2016  British Journal of Nursing  A photopheresis unit, Rotherham NHS Foundation Trust.  Value-stream mapping and identification/elimination of waste, patient scheduling and service structure redesign.  Interrupted time series of 55 patients receiving 140 treatments over a 1-month period. ‘Kaizen’ event 2 months’ post-intervention to measure quality.  Delay in arrival to start of treatment improved 47%. No change to wait for assessment or treatment.  Potential for confounding. Observer bias. No randomisation, lack of controlled design.  Grey literature consideration The NHS is arguably the first and largest healthcare organisation to adopt Lean into practice on a whole-scale manner [19]. However, the final report for PW contains piecemeal quantitative data to reinforce overall efficacy and sustainability [19] and was commissioned by the same division that devised the initiative creating risk of favourable reporting of outcomes [23]. Method of recruitment to the final report is not auditable and confounding is not addressed [19] which leads some of the outcomes to be vulnerable to misinterpretation; an issue inherent in QI measurement in healthcare in general [46]. A systematic review of PW (included in this study) mainly discovered experiential literature and states that few negative reports of PW have been published suggesting this highlights publication bias [23]. Grey literature has not been included in this study to avert risk of including any literature that may be ‘incomplete, biased and distorted’ [27: p.225]. Data extraction Owing to the inclusion of a number of different designs and there being no stand-alone, validated critical appraisal tool for this methodology [47], the Critical Appraisal Tool for Mixed-Methodology Integrative Review (CATMIR) was developed for the purposes of this study. CATMIR is based upon existing and validated critical appraisal tools (AMSTAR [44]; JBI Database Tools [48] and CASP [45]) (seeAppendix A). It was not possible to complete (pooled) meta-analysis as there were either sufficient data or the data were measured in different manners (see Table 2). Table 2 Waiting times and list volume pre- and post-lean intervention Study  Measure  Lodge and Bamford [50]  Modal wait for diagnostics scan (weeks)  Yousri et al. [68]  Volume of patients with door to theatre time in 24 h  McCulloch et al. [52]  Frequency of patients experiencing delay in access to treatment/investigation  Radnor [54]  Use of data within one intervention to reduce diagnostic waiting time (no values given)  Siddique et al. [67]  Mean waiting time for surgery (weeks)  Martin et al. [56]  Volume of hours waiting for radiology scan for diagnostics  Rushton et al. [51]  Volume of minutes for treatment duration and wait for treatment to commence  Study  Measure  Lodge and Bamford [50]  Modal wait for diagnostics scan (weeks)  Yousri et al. [68]  Volume of patients with door to theatre time in 24 h  McCulloch et al. [52]  Frequency of patients experiencing delay in access to treatment/investigation  Radnor [54]  Use of data within one intervention to reduce diagnostic waiting time (no values given)  Siddique et al. [67]  Mean waiting time for surgery (weeks)  Martin et al. [56]  Volume of hours waiting for radiology scan for diagnostics  Rushton et al. [51]  Volume of minutes for treatment duration and wait for treatment to commence  Table 2 Waiting times and list volume pre- and post-lean intervention Study  Measure  Lodge and Bamford [50]  Modal wait for diagnostics scan (weeks)  Yousri et al. [68]  Volume of patients with door to theatre time in 24 h  McCulloch et al. [52]  Frequency of patients experiencing delay in access to treatment/investigation  Radnor [54]  Use of data within one intervention to reduce diagnostic waiting time (no values given)  Siddique et al. [67]  Mean waiting time for surgery (weeks)  Martin et al. [56]  Volume of hours waiting for radiology scan for diagnostics  Rushton et al. [51]  Volume of minutes for treatment duration and wait for treatment to commence  Study  Measure  Lodge and Bamford [50]  Modal wait for diagnostics scan (weeks)  Yousri et al. [68]  Volume of patients with door to theatre time in 24 h  McCulloch et al. [52]  Frequency of patients experiencing delay in access to treatment/investigation  Radnor [54]  Use of data within one intervention to reduce diagnostic waiting time (no values given)  Siddique et al. [67]  Mean waiting time for surgery (weeks)  Martin et al. [56]  Volume of hours waiting for radiology scan for diagnostics  Rushton et al. [51]  Volume of minutes for treatment duration and wait for treatment to commence  Meta-narrative analysis of the literature was completed by first coding and identifying repeated occurrences/patterns in the data using the thematic analysis model suggested by Braun and Clarke [49]. This was then combined with Greenhalgh et al.’s [42] model where ‘storylines’ were identified across the chronology of the literature. Results of data synthesis Critical appraisal Studies achieved a mean CATMIR score of 8.5 (out of 14), with a range of 8 and standard deviation of 2.76. Studies that were more scientific in design (quasi-experimental and systematic review) tended to score more favourably over content analysis, action research and commissioned, peer-reviewed reports (seeAppendix B: CATMIR Matrix). Only one study used a robust experimental design—systematic review [23]. There was also a lack of awareness of confounding across the studies—observers and participants were largely aware of the hypothesis. Two experimental studies introduced new technology as opposed to using existing tools meaning outcome measures could be confounded [50, 51]. One quasi-experimental, interrupted time series study claimed that the Hawthorne effect was unavoidable in their design [52] (studies on the Hawthorne plant of the Western Electric Company, USA noticed behaviour modification in participants (increased productivity) occurred due to the sole act of participation where no intervention was implemented [53]). The secondary research did not consult failed implementations or non-adopters, therefore neutral (control) and/or negative views/figures are absent from the analyses. Sustainability Six of the studies addressed sustainability but only three measured it (by re-testing the data/hypothesis at a later date), two achieved success [50, 51]; the other (a systematic review) [23] gave meta-narrative analysis and largely found a lack of sustainability across the included literature (seeAppendix C—Sustainability Matrix). Experimental designs One study concerning a radiology waiting list redesign asserted correlation between staff perception and sustainability although gave no data to support this [50]. A study on safety and compliance in surgery tested sustainability of one issue (correct deep vein thrombosis (DVT) prophylaxis). Correct DVT prophylaxis rose from 35% (n = 161) pre-intervention to 87% (n = 157) post-intervention and marginally fell over the year (to ~80%) indicating sustained results [52]. Finally, a study concerning waiting and treatment times in a photopheresis unit measured sustainability of the intervention by re-testing the delay between a patient’s arrival and commencement of treatment. There was a fall from 66% to 48% of patients needing to wait over 15 min for treatment; the data were taken pre-intervention and 2 months following intervention although the intervention was simplistic and procedural [51]. Secondary research One large study of routine data and stakeholder interviews asserted that Lean is not a short-term remedy but a longitudinal change of culture [54]. One of the two included NHS Institute commissioned reviews of PW mentioned the importance of the receiving practice culture and system-readiness [21]. Finally, a systematic review of PW offered a narrative review on sustainability; that whole-service adoption is key but that the appetite for Lean may be dwindling due to ‘change fatigue’ [23: p.1368]. Heterogeneity and divergent approaches Adoption and implementation Generally, there were divergent methods of Lean adoption across the studies (seeAppendix D); the most widely used was value-stream/process mapping. Most studies used two distinct aspects of Lean (mode = 2) although one study used six (and achieved the highest CATMIR score) [52]. Four studies concerned the adoption of PW [21, 23, 27, 54]. Study designs Most quasi-experimental studies used an interrupted time series design, one combined this with action research [50], and another incorporated failure mode and effects analysis [55]. One mixed-methods study combined this design with qualitative research [56]. The secondary literature was more diverse where four studies adopted mixed-methods: a large, multi-site study used three case studies [54]; two national studies on PW used routine data, stakeholder interviews and hospital case studies [21, 57]; and another nationwide study conducted content analysis of all annual reports published by NHS organisations [27]. One systematic review of PW largely concerned the UK implementation and was the only included study with a scientifically rigorous design [23]. Outcome measures There were 22 different outcomes measured across the studies; the most common being waiting times with five discovering improvement with statistical evidence and three without. There was further diversity within the outcome measures; these were undertaken in different ways and with different values (see Table 2). Owing to lack of uniformity of measurement in the data, it was not possible to complete meta-analysis. A study testing safety process compliance in surgery did not subject two of the processes to the Lean intervention (PDCA—plan, do, check, act). This led to marginal changes in compliance rates where there were much greater increases in compliance in the outcomes that were subject to PDCA [52]. Discussion The results of this review indicate that there are many competing factors in the study of QI and Lean which contribute to an overall difficulty in achieving clarity. Quality of healthcare cannot be measured and sustained unless it is first defined [58]. Yet definition has proven to be fluid and adaptable; it is malleable depending on economic and political factors [59]. Lean is designed to determine and address intrinsic value yet there are heterogeneous, divergent and global definitions of value [24, 34]. This contributes to variety in the manner of adoption and subsequent diverse study design and measurement. Ambiguity in definition and implementation have contributed to the erosion of a system-wide Lean implementation in an NHS acute trust and formed the focus of a large ethnographic study [29]. Uncertainty and divergence also creates difficulty in achieving a meta-analytical/narrative view. There is also a widely-held view that Lean has been diluted, implemented narrowly and reserved for designated problem areas or specific units [28, 60]. Secondary research has highlighted that favourable results have been lauded and negative experiences under-reported [23, 39]. Critics of Lean assert that ‘healthcare is not directly comparable to manufacturing’ [39: p.134] and cite the differences in influence to output volume between the two; general economic and product demand, respectively. Part of Lean’s popularity amongst organisations is the appeal of continuous QI [10] although many have struggled to sustain results in the medium- to longer-term [61]. Paradoxically, ‘kaizen’ forms a central part of the ideology [62] making it difficult to understand why sustainability is not achieved widely. A common assertion is that success and sustainment of QI is reliant on the recipient culture [35]. However, a systematic review of the diffusion of innovations in the UK health service asserted that definition and measurement of recipient culture is diverse, and that the whole process of examining and measuring QI requires uniformity [63]. The study calls for increase in robust, empirical designs which are otherwise absent [63]. There is also no blueprint to guide the introduction of QI in complex organisations [36]. Plotting the literature in this study over a timeline reveals an evolution from pragmatic (quasi-scientific and experiential) research to more academic and scientific designs. Yet, there continues to be a lack of robust methodological quality which leaves studies vulnerable to problems with internal validity. There are also difficulties as a result of participant observation (where there is greater measured compliance with overt observers in studies on safety) and also where all parties are aware of the hypothesis [64]. The Hawthorne effect has also been seen as an opportunity to improve safety compliance without necessarily implementing anything new or complex [65]. Yet, a safety compliance study [52] did not expose one set of outcome measures to Lean intervention and only achieved marginal results in comparison to greater compliance in PDCA groups. However, safety and compliance have also been positively influenced by interventions that focus on teamwork and culture change alone [66]. Although most studies were not clouded by the introduction of new technology, there remain issues with participant and observer knowledge of hypothesis and/or lack of randomisation in recruitment [51, 55, 67]. The secondary research was generally not inclusive of non-adopting organisations or failed interventions suggesting positive bias in recruitment and therefore publication. Strengths and limitations of the study This is the first literature review of Lean in the NHS that has not been restricted to PW and also included experimental and non-experimental literature. By doing so, it has allowed for consideration of the qualitative aspects of the intervention, statistical analysis and awareness of trends in adoption and implementation. Limitations of this study are the lack of inclusion of grey literature (and theoretical works), wider qualitative research (e.g. aspects of adoption such as staff/patient perceptions completed in single-methods research) and international literature. Hand-searching of printed literature was also not completed. There is a valid debate as to whether a scientific model is appropriate for analysis of Lean given the complexity of studying QI and working-cultures. Although the internal validity of this study is robust, CATMIR tended to score more positively on experimental designs indicating that the tool may require further refinement. Conclusion It continues to be difficult to give an overall conclusion on Lean’s efficacy and sustainability owing to flaws in methodological design leading to uncertainty in results. This review concurs with other evidence citing that there is heterogeneity in definition and divergence in translation to practice alongside the risk of confounding and publication bias [23, 29, 54, 60]. Despite pockets of positive results, the available evidence does not support an overall claim for sustainability of the ideology without other potential confounding issues. More rigorous and controlled designs including a qualitative dimension, particularly with regard to the recipient culture, are needed to be able to form an omniscient view of Lean and its sustainability in today’s NHS. 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One-stop cholecystectomy clinic: an application of lean thinking—can it improve the outcomes? J Perioper Pract  2012; 22: 360– 5. Google Scholar CrossRef Search ADS PubMed  68 Yousri TA, Khan Z, Chakrabarti D et al.  . Lean thinking: can it improve the outcome of fracture neck of femur patients in a district general hospital? Injury  2011; 42: 1234– 7. Google Scholar CrossRef Search ADS PubMed  © The Author(s) 2018. Published by Oxford University Press in association with the International Society for Quality in Health Care. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png International Journal for Quality in Health Care Oxford University Press

Is Lean sustainable in today's NHS hospitals? A systematic literature review using the meta-narrative and integrative methods

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Abstract

Abstract Purpose Methodological variance and quality, heterogeneity of value and divergent approaches are reasons for the varied results of Lean interventions in healthcare despite ongoing global popularity. However, there is piecemeal evidence addressing the sustainability of initiatives—the aim of this review is to use an integrative approach to consider Lean’s sustainability and the quality of available evidence in today’s National Health Service (NHS). Data sources A literature review of AMED, CINAHL, Cochrane, JBI, SCOPUS, DelphiS, MEDLINE, EMBASE, MIDIRS, Web of Science and PsycINFO electronic databases was conducted. Study selection Peer-reviewed studies in NHS hospitals/trusts that concerned undiluted, service-wide Lean adoption and contained quantitative data were included. Reference lists were consulted for evidence via a snowball approach. Methodological quality was assessed using an adapted critical appraisal tool. Data extraction Research design, method of intervention, outcome measures and sustainability were extracted. Results of data synthesis Electronic searches identified 12 studies eligible for inclusion. This comprised of five quasi-experimental designs (one mixed-method), three multi-site analyses, one action research, one failure mode and effects analysis, one content analysis of annual reports and one systematic review. Six articles considered sustainability with two of these providing measured successes. Despite diverse and positive outcomes studies lacked scientific rigour, failed to consider confounding issues, were at risk of positive bias and did not demonstrate sustainability with any statistical significance. Conclusion Lean has ostensible value but it is difficult to draw a conclusion on efficacy or sustainability. Higher quality scientific research into Lean and the effect of staffing cultures on initiatives are needed to ascertain the extent that Lean can affect healthcare quality and subsequently be sustained. quality measurement, quality management, quality improvement, quality management, leadership, quality management, quality culture, quality management, audit, external quality assessment Introduction There has been increasing movement in recent years to improve the quality of care provided by the National Health Service (NHS) alongside pressure for growth in efficiency and reduction in costs. Governmental and NHS policies, documents and reports have addressed this directly, suggesting various quality improvement (QI) methodologies [1–4]. The last 20 years have also seen growth in productivity in the NHS stagnating in comparison with the UK economy [3] generating widespread call to create whole-scale and disruptive change to the current health sector status quo [3–5]. To address the crisis in funding and efficiency [5], the NHS has turned to a number of QI ideologies, often originally described or discovered outside the health sector [6]. The methodology used by automotive manufacturer Toyota has gathered specific attention—a 5-year study from the Massachussetts Institute of Technology coined these processes as ‘Lean’ [7]. Lean is defined as a continuous QI methodology intended to remove waste, create efficiency and improve safety from the perspective of the end-user. Toyota’s success was cited and measured by the reduction in defects and factory floor space, savings in costs and worker satisfaction—a change in working culture and not necessarily new tools and equipment [8]. The paradigm of Lean is to evaluate the process or production flow (termed ‘value stream’) and identify areas where waste is being created prior to eliminating it [9]. Lean has become a global management phenomenon having been applied to health-sectors internationally [10]. Transparency in its values and broad applicability means Lean has often been simplified for healthcare adoption [11]; methods such as the 5 S’s (sort, set in order, shine, standardise and sustain) have been used and applied to a range of settings [12]. Inherent in Lean is the Japanese notion of ‘kaizen’ which refers to continuous QI—rechecking processes and making adjustments. Kaizen is necessary for Lean to be sustainable, however, ensuring it occurs within the framework of organisational change can be difficult [13]. Lean’s efficacy is promoted in a number of healthcare areas, but there is little evidence directly addressing its sustainability in broad health service adoption [14]. Over the last decade, the NHS has introduced Lean methodology tentatively as a suggestion [15, 16], more firmly in policy [17, 18] and a nationwide initiative [19] with a view to addressing the necessary changes. This has been with conflicting or ambiguous supporting evidence where both diluted [15] and undiluted implementations have been promoted as necessary by the same author [4, 15, 19]. Yet, this is not reflected in the cited evidence [20] where undiluted and system-wide adoption is deemed more beneficial. Despite lack of systematic evidence supporting efficacy, the NHS introduced ‘The Productive Ward: Releasing Time to Care’ [19] (referred to in this study as PW—the trademarked package, not generic terms or interventions) nationwide in 2007. The program of modules was widely adopted [19] and supported [21] then later sold internationally [22]. PW remains in its infancy, with no clear evidence-based conclusion over its efficacy despite global uptake [23, 24]. In 2014, the Department of Health went on to incorporate Lean methodology into national health policy. ‘The new era of thinking and practice in change and transformation: A call to action for leaders of health and care’ [4] asserts that Lean is tried, tested and proven to be successful [4]. However, contemporaneous systematic evidence suggests there is positive publication bias in PW [23] that direct application of Lean to healthcare is suboptimal [6] and that there continues to be a gap between theory and practice [25]. The national policy, written by the one of the authors of PW, states that it is ‘time for heresy’ [4: p.22] and calls for whole-scale, disruptive change to healthcare, specifically promoting Lean to achieve this [4]. However, there is continued debate and uncertainty around Lean’s overall efficacy [26], its applicability to practice [27], manner of adoption [28] and sustainability [29]. Infancy in its development compared with its sector of origin [30] is cited as contributory to this. There also remains agreement that the quality and nature of evidence is mixed [31] or poor [32], continuously evolving and not finite [33]. However, manner of adaptation to practice and the recipient practice culture are paramount to success [34, 35]. There is also a central issue—that research into large-scale transformational change in complex organisations is problematic—there is little referential evidence [36] alongside a lack of a universal scale for measuring Lean, making appraisal of its efficacy and sustainability difficult [37]. However, the ostensible view of Lean in the NHS is one of positivity: wide adoption [19], uptake [23] and the genesis of profitable international commoditisation [38]; Lean has been promoted as a necessary panacea [39]. The intention of this study is to address this gap in knowledge [25] with reference to sustainability, in particular, the dearth of sustained results of implementations [14] alongside a tendency for studies to mention, but not explicitly address sustainability [26]. Methods An integrative literature review incorporates mixed-designs and theoretical literature alongside controlled study designs to provide comprehensive analysis; it is an important tool to improve the science and practice of healthcare and gives a rounded view of a complex intervention [40]. This study adopts an integrative approach as outlined by Torraco [41] alongside a meta-narrative approach to literature review as suggested by Greenhalgh et al. [42]. Data sources Comprehensive searches were conducted of the following electronic databases: AMED, CINAHL, Cochrane Database, DelphiS, EMBASE, JBI Database, MEDLINE, MIDIRS, PsycINFO, SCOPUS and Web of Science. The keywords ‘lean’, ‘productiv*’, ‘releasing time’ and also ‘time to care’ were entered to conduct the searches. Various Boolean (AND/OR) operators were applied in order to increase the size of search results. There was no restriction on year of publication although filters were applied for peer-reviewed, published literature in combination with a geographical filter for studies in the UK. Only articles published in the English Language were included. Study selection This process has been mapped in Fig. 1. In order to be included in the study, an article had to satisfy the following criteria: primary or secondary peer-reviewed literature that focuses on a clear (undiluted) Lean intervention where there is measurement of the intervention itself. The study must be evaluating the whole adoption over an aspect of Lean redesign. The broad criteria allowed a variety of sources to become eligible for consideration whilst simultaneously excluding news reports, small case or individual studies/stories that lacked depth of data field/academic rigour. Defining the Lean intervention as undiluted reduced the risk of inherent confounding and adhered to the theoretical basis of Lean needing to be a whole-scale and cultural adoption [20]. There was no restriction on the date of publication in the knowledge that this was self-limiting owing to the recent boom in interest in Lean healthcare [35]. Figure 1 View largeDownload slide PRISMA [43] flow diagram. Figure 1 View largeDownload slide PRISMA [43] flow diagram. The identification of articles included in this review was completed in four stages: (i) the initial search results of 5127 articles were examined to remove anything duplicate or deemed irrelevant. A reduced list of 101 articles was then subject to the (ii) snowball approach where reference lists were scanned and 44 additional references were gleamed. (iii) Further duplicate removal, and inspection of abstracts then occurred and a short-list of 32 articles was compiled. These were then subject to (iv) a full-text, methodological review where the size of the presented data field was inspected; validated critical appraisal tools (AMSTAR [44] and CASP [45]) were used to verify decisions with regard to inclusion; this process provided the final 12 studies for inclusion—see Table 1. Table 1 Detailed list of literature eligible for inclusion in the review Title  Author(s)  Year  Journal  Setting  Intervention  Method  Outcome  Limitations  New development: using lean techniques to reduce radiology waiting times  Lodge A and Bamford D  2008  Public Money and Management  The division of diagnostics and clinical support—Pennine Acute Hospital Trust. 2000 staff and 150 medical consultants.  Value-stream mapping —construction of an intranet-based waiting list.  Action research: (quasi-experimental—interrupted time) study of the division of diagnostics and clinical support.  Reduction in modal waiting times of 25–50% in different departments.  No statement of limitations or ethical consideration. Internal validity: no awareness of confounding despite clear potential for confounding (new technology).  Application of lean principles can reduce inpatient prescription dispensing times  Beard J and Wood D  2010  The Pharmaceutical Journal  Pharmacy Department of Musgrove Hospital, Taunton and Somerset NHS Trust—Inpatient Dispensary.  Process and value mapping and failure mode effect of current processes. PDCA.  Failure mode effects analysis; continuous re-evaluation of the process. Aspects of interrupted time series.  Median dispensing times reduced from 188 min to 27 min (SD 7 min). Error rates unchanged.  Bias: observers were aware of the hypothesis. There was a lack of control to the study—no comparative group (aside from baseline working). Possibility of confounding (Hawthorne)  Effect of a ‘Lean’ intervention to improve safety processes and outcomes on a surgical emergency unit  McCulloch P, Kreckler S, New S, Yezen S, Handa A, and Catchpole K  2010  BMJ  Emergency General Surgery Ward—John Radcliffe Hospital (38 beds)  Targeting five of the seven care processes relevant to patient safety incorporating The five S’s Process Mapping Error Visibility Elimination of Waste PDCA  Quasi-experimental interrupted time series study of 38 bed units where 969 patients were admitted before intervention, 1114 admitted after intervention was implemented.  Patients requiring ward admission fell 27–20%. Adverse events were unchanged (factors felt to be external to intervention)  No clear randomisation or blinding in samples for study. Observers were aware of hypothesis.  Lean thinking: can it improve the outcome of fracture neck of femur patients in a district general hospital?  Yousri TA, Khan Z, Chakrabarti D, Fernandes R, and Wahab K  2011  Injury  Fracture neck of femur patients at Goodhope Hospital (NHS).  Value-stream approach was applied to patients admitted—identification and elimination of waste.  Quasi-experimental interrupted time series: 608 patients in total were recruited—309 pre-lean, 299 post-intervention.  Statistically significant reduction in 30 days (5%) and overall (9.3%) mortality. Reduction in door to theatre times, bed usage and increase in early discharge.  No statement of limitation or ethical consideration. Internal validity: no awareness of confounding. Risk of bias from observers.  Implementing lean in healthcare: making the link between the approach, readiness and sustainability  Radnor Z  2011  International Journal of Industrial Engineering and Management  Two NHS acute hospitals and one NHS mental health trust.  Various interventions across each provider—included ‘rapid improvement events’, value-stream mapping and PW-based initiatives.  Mixed-method secondary research of a range of data from the interventions. Analysis of three case studies consisting of 55 interviews and 13 focus groups.  Suggests a model or framework for further lean implementation and comments on the sustainability of each intervention.  Bias risk—Recruitment to study: three large and useful case studies but no systematic approach to recruitment—no clear statement of rationale for this. No ethical consideration.  The adoption, local implementation and assimilation into routine nursing practice of a national quality improvement programme: The Productive Ward in England  Robert G, Morrow E, Maben J, Griffiths P, and Callard L  2011  Journal of Clinical Nursing  Routine data, online survey of 150 respondents and 58 interviews across five organisations.  Analysis of PW—secondary research not individual intervention or case-control.  Mixed-method secondary research (analysis of routine data, online survey, interviews).  Provides outcomes for a range of interventions in a range of settings.  Bias risk—recruitment to study; no systematic approach. Research funded by NHSI (creator of PW). Broad, unspecific issue. No inclusion of ‘control’ or failure groups for comparison.  Implementing large-scale quality improvement: lessons from The Productive Ward: Releasing Time to Care.  Morrow E, Robert G, Maben J, and Griffiths P  2012  International Journal of Health Care Quality Assurance  Large-scale research across a number of organisations in the NHS.  Range of methods implemented across the various environments—largely ‘productive ward/releasing time to care’.  Mixed-method 15 semi-structured interviews of national-level policy-makers, 150 surveys of senior managers, five hospital case studies involving 58 staff.  Implementation was widely supported but various facilitators and challenges were identified.  Bias risk—recruitment to study. Funded by NHSI (creator of PW). Large and non-specific goal/aim of study. No ethical consideration. Recruitment strategy non-randomised and unclear.  One-stop cholecystectomy clinic: an application of lean thinking—can it improve the outcomes?  Siddique K, Effat S, Elsayed A, Cheema R, Mirza S, and Basu S  2012  Journal of Perioperative Practice  General Surgery Department, William Harvey Hospital, Kent. DGH of 550 beds serving 300 000 people.  A ‘one-stop’ surgical intervention where the patient undergoes the preoperative assessment and surgery in the same visit.  Interrupted time series quasi-experimental. About 141 medical records reviewed, 12 excluded. This cohort was compared with a routine cohort.  Number of hospital visits and preoperative admissions lower in one-stop patients. Waiting times were reduced.  No consideration of confounding or Hawthorne effect. Non-controlled method, no randomisation. Observer bias. No awareness of limitations.  Evaluating Lean in healthcare  Burgess N and Radnor Z  2013  International Journal of Healthcare Quality Assurance  Analysis of a number of English hospitals (NHS).  Various interventions employed by a large number of organisations nationally.  Lean implementation snapshots: content analysis of all annual reports and websites over two time periods.  Divergent approaches to Lean interventions identified. Implementation tends to be isolated rather than system-wide.  Bias risk—recruitment to study strategy unclear. Nature of study design is questionable to achieve stated aims. Results of study are unclear. No ethical considerations.  A mixed model study evaluating lean in the transformation of an Orthopaedic Radiology service  Martin AJ, Hogg P, and Mackay S  2013  Radiography  Radiology Department of Royal Bolton Hospital (NHS).  Value-stream identification and implementation.  Mixed-method analysis of qualitative and quantitative outcomes prior to and post-lean intervention. Questionnaires of both patients and staff.  About 50% and 60% reductions in pathway lengths, 60–69% reduction in patient waiting times. Better quality of patient and staff experience post-intervention. Improvement in patient waiting times.  No acknowledgement of confounding—new service with new technology. Significantly larger amount of respondents post-intervention. Unclear results of study. No ethical considerations. Observer bias.  A systematic literature review of Releasing Time to Care: the Productive Ward  Wright S and McSherry W  2013  Journal of Clinical Nursing  Review of literature across a number of settings.  A number of interventions applied across the different areas of research.  Systematic review of 18 articles identified following a comprehensive literature search.  Safety improvement and reduction of infection. Potential positive publication/results bias. Benefit to patients, frontline staff and cost-savings.  No ethical consideration of cited papers. No acknowledgement of limitations of study.  Improving the service for patients receiving extracorporeal photopheresis using Lean principles  Rushton C, Robertson L, Taylor T, Taylor P, Button P, and Alfred A  2016  British Journal of Nursing  A photopheresis unit, Rotherham NHS Foundation Trust.  Value-stream mapping and identification/elimination of waste, patient scheduling and service structure redesign.  Interrupted time series of 55 patients receiving 140 treatments over a 1-month period. ‘Kaizen’ event 2 months’ post-intervention to measure quality.  Delay in arrival to start of treatment improved 47%. No change to wait for assessment or treatment.  Potential for confounding. Observer bias. No randomisation, lack of controlled design.  Title  Author(s)  Year  Journal  Setting  Intervention  Method  Outcome  Limitations  New development: using lean techniques to reduce radiology waiting times  Lodge A and Bamford D  2008  Public Money and Management  The division of diagnostics and clinical support—Pennine Acute Hospital Trust. 2000 staff and 150 medical consultants.  Value-stream mapping —construction of an intranet-based waiting list.  Action research: (quasi-experimental—interrupted time) study of the division of diagnostics and clinical support.  Reduction in modal waiting times of 25–50% in different departments.  No statement of limitations or ethical consideration. Internal validity: no awareness of confounding despite clear potential for confounding (new technology).  Application of lean principles can reduce inpatient prescription dispensing times  Beard J and Wood D  2010  The Pharmaceutical Journal  Pharmacy Department of Musgrove Hospital, Taunton and Somerset NHS Trust—Inpatient Dispensary.  Process and value mapping and failure mode effect of current processes. PDCA.  Failure mode effects analysis; continuous re-evaluation of the process. Aspects of interrupted time series.  Median dispensing times reduced from 188 min to 27 min (SD 7 min). Error rates unchanged.  Bias: observers were aware of the hypothesis. There was a lack of control to the study—no comparative group (aside from baseline working). Possibility of confounding (Hawthorne)  Effect of a ‘Lean’ intervention to improve safety processes and outcomes on a surgical emergency unit  McCulloch P, Kreckler S, New S, Yezen S, Handa A, and Catchpole K  2010  BMJ  Emergency General Surgery Ward—John Radcliffe Hospital (38 beds)  Targeting five of the seven care processes relevant to patient safety incorporating The five S’s Process Mapping Error Visibility Elimination of Waste PDCA  Quasi-experimental interrupted time series study of 38 bed units where 969 patients were admitted before intervention, 1114 admitted after intervention was implemented.  Patients requiring ward admission fell 27–20%. Adverse events were unchanged (factors felt to be external to intervention)  No clear randomisation or blinding in samples for study. Observers were aware of hypothesis.  Lean thinking: can it improve the outcome of fracture neck of femur patients in a district general hospital?  Yousri TA, Khan Z, Chakrabarti D, Fernandes R, and Wahab K  2011  Injury  Fracture neck of femur patients at Goodhope Hospital (NHS).  Value-stream approach was applied to patients admitted—identification and elimination of waste.  Quasi-experimental interrupted time series: 608 patients in total were recruited—309 pre-lean, 299 post-intervention.  Statistically significant reduction in 30 days (5%) and overall (9.3%) mortality. Reduction in door to theatre times, bed usage and increase in early discharge.  No statement of limitation or ethical consideration. Internal validity: no awareness of confounding. Risk of bias from observers.  Implementing lean in healthcare: making the link between the approach, readiness and sustainability  Radnor Z  2011  International Journal of Industrial Engineering and Management  Two NHS acute hospitals and one NHS mental health trust.  Various interventions across each provider—included ‘rapid improvement events’, value-stream mapping and PW-based initiatives.  Mixed-method secondary research of a range of data from the interventions. Analysis of three case studies consisting of 55 interviews and 13 focus groups.  Suggests a model or framework for further lean implementation and comments on the sustainability of each intervention.  Bias risk—Recruitment to study: three large and useful case studies but no systematic approach to recruitment—no clear statement of rationale for this. No ethical consideration.  The adoption, local implementation and assimilation into routine nursing practice of a national quality improvement programme: The Productive Ward in England  Robert G, Morrow E, Maben J, Griffiths P, and Callard L  2011  Journal of Clinical Nursing  Routine data, online survey of 150 respondents and 58 interviews across five organisations.  Analysis of PW—secondary research not individual intervention or case-control.  Mixed-method secondary research (analysis of routine data, online survey, interviews).  Provides outcomes for a range of interventions in a range of settings.  Bias risk—recruitment to study; no systematic approach. Research funded by NHSI (creator of PW). Broad, unspecific issue. No inclusion of ‘control’ or failure groups for comparison.  Implementing large-scale quality improvement: lessons from The Productive Ward: Releasing Time to Care.  Morrow E, Robert G, Maben J, and Griffiths P  2012  International Journal of Health Care Quality Assurance  Large-scale research across a number of organisations in the NHS.  Range of methods implemented across the various environments—largely ‘productive ward/releasing time to care’.  Mixed-method 15 semi-structured interviews of national-level policy-makers, 150 surveys of senior managers, five hospital case studies involving 58 staff.  Implementation was widely supported but various facilitators and challenges were identified.  Bias risk—recruitment to study. Funded by NHSI (creator of PW). Large and non-specific goal/aim of study. No ethical consideration. Recruitment strategy non-randomised and unclear.  One-stop cholecystectomy clinic: an application of lean thinking—can it improve the outcomes?  Siddique K, Effat S, Elsayed A, Cheema R, Mirza S, and Basu S  2012  Journal of Perioperative Practice  General Surgery Department, William Harvey Hospital, Kent. DGH of 550 beds serving 300 000 people.  A ‘one-stop’ surgical intervention where the patient undergoes the preoperative assessment and surgery in the same visit.  Interrupted time series quasi-experimental. About 141 medical records reviewed, 12 excluded. This cohort was compared with a routine cohort.  Number of hospital visits and preoperative admissions lower in one-stop patients. Waiting times were reduced.  No consideration of confounding or Hawthorne effect. Non-controlled method, no randomisation. Observer bias. No awareness of limitations.  Evaluating Lean in healthcare  Burgess N and Radnor Z  2013  International Journal of Healthcare Quality Assurance  Analysis of a number of English hospitals (NHS).  Various interventions employed by a large number of organisations nationally.  Lean implementation snapshots: content analysis of all annual reports and websites over two time periods.  Divergent approaches to Lean interventions identified. Implementation tends to be isolated rather than system-wide.  Bias risk—recruitment to study strategy unclear. Nature of study design is questionable to achieve stated aims. Results of study are unclear. No ethical considerations.  A mixed model study evaluating lean in the transformation of an Orthopaedic Radiology service  Martin AJ, Hogg P, and Mackay S  2013  Radiography  Radiology Department of Royal Bolton Hospital (NHS).  Value-stream identification and implementation.  Mixed-method analysis of qualitative and quantitative outcomes prior to and post-lean intervention. Questionnaires of both patients and staff.  About 50% and 60% reductions in pathway lengths, 60–69% reduction in patient waiting times. Better quality of patient and staff experience post-intervention. Improvement in patient waiting times.  No acknowledgement of confounding—new service with new technology. Significantly larger amount of respondents post-intervention. Unclear results of study. No ethical considerations. Observer bias.  A systematic literature review of Releasing Time to Care: the Productive Ward  Wright S and McSherry W  2013  Journal of Clinical Nursing  Review of literature across a number of settings.  A number of interventions applied across the different areas of research.  Systematic review of 18 articles identified following a comprehensive literature search.  Safety improvement and reduction of infection. Potential positive publication/results bias. Benefit to patients, frontline staff and cost-savings.  No ethical consideration of cited papers. No acknowledgement of limitations of study.  Improving the service for patients receiving extracorporeal photopheresis using Lean principles  Rushton C, Robertson L, Taylor T, Taylor P, Button P, and Alfred A  2016  British Journal of Nursing  A photopheresis unit, Rotherham NHS Foundation Trust.  Value-stream mapping and identification/elimination of waste, patient scheduling and service structure redesign.  Interrupted time series of 55 patients receiving 140 treatments over a 1-month period. ‘Kaizen’ event 2 months’ post-intervention to measure quality.  Delay in arrival to start of treatment improved 47%. No change to wait for assessment or treatment.  Potential for confounding. Observer bias. No randomisation, lack of controlled design.  Table 1 Detailed list of literature eligible for inclusion in the review Title  Author(s)  Year  Journal  Setting  Intervention  Method  Outcome  Limitations  New development: using lean techniques to reduce radiology waiting times  Lodge A and Bamford D  2008  Public Money and Management  The division of diagnostics and clinical support—Pennine Acute Hospital Trust. 2000 staff and 150 medical consultants.  Value-stream mapping —construction of an intranet-based waiting list.  Action research: (quasi-experimental—interrupted time) study of the division of diagnostics and clinical support.  Reduction in modal waiting times of 25–50% in different departments.  No statement of limitations or ethical consideration. Internal validity: no awareness of confounding despite clear potential for confounding (new technology).  Application of lean principles can reduce inpatient prescription dispensing times  Beard J and Wood D  2010  The Pharmaceutical Journal  Pharmacy Department of Musgrove Hospital, Taunton and Somerset NHS Trust—Inpatient Dispensary.  Process and value mapping and failure mode effect of current processes. PDCA.  Failure mode effects analysis; continuous re-evaluation of the process. Aspects of interrupted time series.  Median dispensing times reduced from 188 min to 27 min (SD 7 min). Error rates unchanged.  Bias: observers were aware of the hypothesis. There was a lack of control to the study—no comparative group (aside from baseline working). Possibility of confounding (Hawthorne)  Effect of a ‘Lean’ intervention to improve safety processes and outcomes on a surgical emergency unit  McCulloch P, Kreckler S, New S, Yezen S, Handa A, and Catchpole K  2010  BMJ  Emergency General Surgery Ward—John Radcliffe Hospital (38 beds)  Targeting five of the seven care processes relevant to patient safety incorporating The five S’s Process Mapping Error Visibility Elimination of Waste PDCA  Quasi-experimental interrupted time series study of 38 bed units where 969 patients were admitted before intervention, 1114 admitted after intervention was implemented.  Patients requiring ward admission fell 27–20%. Adverse events were unchanged (factors felt to be external to intervention)  No clear randomisation or blinding in samples for study. Observers were aware of hypothesis.  Lean thinking: can it improve the outcome of fracture neck of femur patients in a district general hospital?  Yousri TA, Khan Z, Chakrabarti D, Fernandes R, and Wahab K  2011  Injury  Fracture neck of femur patients at Goodhope Hospital (NHS).  Value-stream approach was applied to patients admitted—identification and elimination of waste.  Quasi-experimental interrupted time series: 608 patients in total were recruited—309 pre-lean, 299 post-intervention.  Statistically significant reduction in 30 days (5%) and overall (9.3%) mortality. Reduction in door to theatre times, bed usage and increase in early discharge.  No statement of limitation or ethical consideration. Internal validity: no awareness of confounding. Risk of bias from observers.  Implementing lean in healthcare: making the link between the approach, readiness and sustainability  Radnor Z  2011  International Journal of Industrial Engineering and Management  Two NHS acute hospitals and one NHS mental health trust.  Various interventions across each provider—included ‘rapid improvement events’, value-stream mapping and PW-based initiatives.  Mixed-method secondary research of a range of data from the interventions. Analysis of three case studies consisting of 55 interviews and 13 focus groups.  Suggests a model or framework for further lean implementation and comments on the sustainability of each intervention.  Bias risk—Recruitment to study: three large and useful case studies but no systematic approach to recruitment—no clear statement of rationale for this. No ethical consideration.  The adoption, local implementation and assimilation into routine nursing practice of a national quality improvement programme: The Productive Ward in England  Robert G, Morrow E, Maben J, Griffiths P, and Callard L  2011  Journal of Clinical Nursing  Routine data, online survey of 150 respondents and 58 interviews across five organisations.  Analysis of PW—secondary research not individual intervention or case-control.  Mixed-method secondary research (analysis of routine data, online survey, interviews).  Provides outcomes for a range of interventions in a range of settings.  Bias risk—recruitment to study; no systematic approach. Research funded by NHSI (creator of PW). Broad, unspecific issue. No inclusion of ‘control’ or failure groups for comparison.  Implementing large-scale quality improvement: lessons from The Productive Ward: Releasing Time to Care.  Morrow E, Robert G, Maben J, and Griffiths P  2012  International Journal of Health Care Quality Assurance  Large-scale research across a number of organisations in the NHS.  Range of methods implemented across the various environments—largely ‘productive ward/releasing time to care’.  Mixed-method 15 semi-structured interviews of national-level policy-makers, 150 surveys of senior managers, five hospital case studies involving 58 staff.  Implementation was widely supported but various facilitators and challenges were identified.  Bias risk—recruitment to study. Funded by NHSI (creator of PW). Large and non-specific goal/aim of study. No ethical consideration. Recruitment strategy non-randomised and unclear.  One-stop cholecystectomy clinic: an application of lean thinking—can it improve the outcomes?  Siddique K, Effat S, Elsayed A, Cheema R, Mirza S, and Basu S  2012  Journal of Perioperative Practice  General Surgery Department, William Harvey Hospital, Kent. DGH of 550 beds serving 300 000 people.  A ‘one-stop’ surgical intervention where the patient undergoes the preoperative assessment and surgery in the same visit.  Interrupted time series quasi-experimental. About 141 medical records reviewed, 12 excluded. This cohort was compared with a routine cohort.  Number of hospital visits and preoperative admissions lower in one-stop patients. Waiting times were reduced.  No consideration of confounding or Hawthorne effect. Non-controlled method, no randomisation. Observer bias. No awareness of limitations.  Evaluating Lean in healthcare  Burgess N and Radnor Z  2013  International Journal of Healthcare Quality Assurance  Analysis of a number of English hospitals (NHS).  Various interventions employed by a large number of organisations nationally.  Lean implementation snapshots: content analysis of all annual reports and websites over two time periods.  Divergent approaches to Lean interventions identified. Implementation tends to be isolated rather than system-wide.  Bias risk—recruitment to study strategy unclear. Nature of study design is questionable to achieve stated aims. Results of study are unclear. No ethical considerations.  A mixed model study evaluating lean in the transformation of an Orthopaedic Radiology service  Martin AJ, Hogg P, and Mackay S  2013  Radiography  Radiology Department of Royal Bolton Hospital (NHS).  Value-stream identification and implementation.  Mixed-method analysis of qualitative and quantitative outcomes prior to and post-lean intervention. Questionnaires of both patients and staff.  About 50% and 60% reductions in pathway lengths, 60–69% reduction in patient waiting times. Better quality of patient and staff experience post-intervention. Improvement in patient waiting times.  No acknowledgement of confounding—new service with new technology. Significantly larger amount of respondents post-intervention. Unclear results of study. No ethical considerations. Observer bias.  A systematic literature review of Releasing Time to Care: the Productive Ward  Wright S and McSherry W  2013  Journal of Clinical Nursing  Review of literature across a number of settings.  A number of interventions applied across the different areas of research.  Systematic review of 18 articles identified following a comprehensive literature search.  Safety improvement and reduction of infection. Potential positive publication/results bias. Benefit to patients, frontline staff and cost-savings.  No ethical consideration of cited papers. No acknowledgement of limitations of study.  Improving the service for patients receiving extracorporeal photopheresis using Lean principles  Rushton C, Robertson L, Taylor T, Taylor P, Button P, and Alfred A  2016  British Journal of Nursing  A photopheresis unit, Rotherham NHS Foundation Trust.  Value-stream mapping and identification/elimination of waste, patient scheduling and service structure redesign.  Interrupted time series of 55 patients receiving 140 treatments over a 1-month period. ‘Kaizen’ event 2 months’ post-intervention to measure quality.  Delay in arrival to start of treatment improved 47%. No change to wait for assessment or treatment.  Potential for confounding. Observer bias. No randomisation, lack of controlled design.  Title  Author(s)  Year  Journal  Setting  Intervention  Method  Outcome  Limitations  New development: using lean techniques to reduce radiology waiting times  Lodge A and Bamford D  2008  Public Money and Management  The division of diagnostics and clinical support—Pennine Acute Hospital Trust. 2000 staff and 150 medical consultants.  Value-stream mapping —construction of an intranet-based waiting list.  Action research: (quasi-experimental—interrupted time) study of the division of diagnostics and clinical support.  Reduction in modal waiting times of 25–50% in different departments.  No statement of limitations or ethical consideration. Internal validity: no awareness of confounding despite clear potential for confounding (new technology).  Application of lean principles can reduce inpatient prescription dispensing times  Beard J and Wood D  2010  The Pharmaceutical Journal  Pharmacy Department of Musgrove Hospital, Taunton and Somerset NHS Trust—Inpatient Dispensary.  Process and value mapping and failure mode effect of current processes. PDCA.  Failure mode effects analysis; continuous re-evaluation of the process. Aspects of interrupted time series.  Median dispensing times reduced from 188 min to 27 min (SD 7 min). Error rates unchanged.  Bias: observers were aware of the hypothesis. There was a lack of control to the study—no comparative group (aside from baseline working). Possibility of confounding (Hawthorne)  Effect of a ‘Lean’ intervention to improve safety processes and outcomes on a surgical emergency unit  McCulloch P, Kreckler S, New S, Yezen S, Handa A, and Catchpole K  2010  BMJ  Emergency General Surgery Ward—John Radcliffe Hospital (38 beds)  Targeting five of the seven care processes relevant to patient safety incorporating The five S’s Process Mapping Error Visibility Elimination of Waste PDCA  Quasi-experimental interrupted time series study of 38 bed units where 969 patients were admitted before intervention, 1114 admitted after intervention was implemented.  Patients requiring ward admission fell 27–20%. Adverse events were unchanged (factors felt to be external to intervention)  No clear randomisation or blinding in samples for study. Observers were aware of hypothesis.  Lean thinking: can it improve the outcome of fracture neck of femur patients in a district general hospital?  Yousri TA, Khan Z, Chakrabarti D, Fernandes R, and Wahab K  2011  Injury  Fracture neck of femur patients at Goodhope Hospital (NHS).  Value-stream approach was applied to patients admitted—identification and elimination of waste.  Quasi-experimental interrupted time series: 608 patients in total were recruited—309 pre-lean, 299 post-intervention.  Statistically significant reduction in 30 days (5%) and overall (9.3%) mortality. Reduction in door to theatre times, bed usage and increase in early discharge.  No statement of limitation or ethical consideration. Internal validity: no awareness of confounding. Risk of bias from observers.  Implementing lean in healthcare: making the link between the approach, readiness and sustainability  Radnor Z  2011  International Journal of Industrial Engineering and Management  Two NHS acute hospitals and one NHS mental health trust.  Various interventions across each provider—included ‘rapid improvement events’, value-stream mapping and PW-based initiatives.  Mixed-method secondary research of a range of data from the interventions. Analysis of three case studies consisting of 55 interviews and 13 focus groups.  Suggests a model or framework for further lean implementation and comments on the sustainability of each intervention.  Bias risk—Recruitment to study: three large and useful case studies but no systematic approach to recruitment—no clear statement of rationale for this. No ethical consideration.  The adoption, local implementation and assimilation into routine nursing practice of a national quality improvement programme: The Productive Ward in England  Robert G, Morrow E, Maben J, Griffiths P, and Callard L  2011  Journal of Clinical Nursing  Routine data, online survey of 150 respondents and 58 interviews across five organisations.  Analysis of PW—secondary research not individual intervention or case-control.  Mixed-method secondary research (analysis of routine data, online survey, interviews).  Provides outcomes for a range of interventions in a range of settings.  Bias risk—recruitment to study; no systematic approach. Research funded by NHSI (creator of PW). Broad, unspecific issue. No inclusion of ‘control’ or failure groups for comparison.  Implementing large-scale quality improvement: lessons from The Productive Ward: Releasing Time to Care.  Morrow E, Robert G, Maben J, and Griffiths P  2012  International Journal of Health Care Quality Assurance  Large-scale research across a number of organisations in the NHS.  Range of methods implemented across the various environments—largely ‘productive ward/releasing time to care’.  Mixed-method 15 semi-structured interviews of national-level policy-makers, 150 surveys of senior managers, five hospital case studies involving 58 staff.  Implementation was widely supported but various facilitators and challenges were identified.  Bias risk—recruitment to study. Funded by NHSI (creator of PW). Large and non-specific goal/aim of study. No ethical consideration. Recruitment strategy non-randomised and unclear.  One-stop cholecystectomy clinic: an application of lean thinking—can it improve the outcomes?  Siddique K, Effat S, Elsayed A, Cheema R, Mirza S, and Basu S  2012  Journal of Perioperative Practice  General Surgery Department, William Harvey Hospital, Kent. DGH of 550 beds serving 300 000 people.  A ‘one-stop’ surgical intervention where the patient undergoes the preoperative assessment and surgery in the same visit.  Interrupted time series quasi-experimental. About 141 medical records reviewed, 12 excluded. This cohort was compared with a routine cohort.  Number of hospital visits and preoperative admissions lower in one-stop patients. Waiting times were reduced.  No consideration of confounding or Hawthorne effect. Non-controlled method, no randomisation. Observer bias. No awareness of limitations.  Evaluating Lean in healthcare  Burgess N and Radnor Z  2013  International Journal of Healthcare Quality Assurance  Analysis of a number of English hospitals (NHS).  Various interventions employed by a large number of organisations nationally.  Lean implementation snapshots: content analysis of all annual reports and websites over two time periods.  Divergent approaches to Lean interventions identified. Implementation tends to be isolated rather than system-wide.  Bias risk—recruitment to study strategy unclear. Nature of study design is questionable to achieve stated aims. Results of study are unclear. No ethical considerations.  A mixed model study evaluating lean in the transformation of an Orthopaedic Radiology service  Martin AJ, Hogg P, and Mackay S  2013  Radiography  Radiology Department of Royal Bolton Hospital (NHS).  Value-stream identification and implementation.  Mixed-method analysis of qualitative and quantitative outcomes prior to and post-lean intervention. Questionnaires of both patients and staff.  About 50% and 60% reductions in pathway lengths, 60–69% reduction in patient waiting times. Better quality of patient and staff experience post-intervention. Improvement in patient waiting times.  No acknowledgement of confounding—new service with new technology. Significantly larger amount of respondents post-intervention. Unclear results of study. No ethical considerations. Observer bias.  A systematic literature review of Releasing Time to Care: the Productive Ward  Wright S and McSherry W  2013  Journal of Clinical Nursing  Review of literature across a number of settings.  A number of interventions applied across the different areas of research.  Systematic review of 18 articles identified following a comprehensive literature search.  Safety improvement and reduction of infection. Potential positive publication/results bias. Benefit to patients, frontline staff and cost-savings.  No ethical consideration of cited papers. No acknowledgement of limitations of study.  Improving the service for patients receiving extracorporeal photopheresis using Lean principles  Rushton C, Robertson L, Taylor T, Taylor P, Button P, and Alfred A  2016  British Journal of Nursing  A photopheresis unit, Rotherham NHS Foundation Trust.  Value-stream mapping and identification/elimination of waste, patient scheduling and service structure redesign.  Interrupted time series of 55 patients receiving 140 treatments over a 1-month period. ‘Kaizen’ event 2 months’ post-intervention to measure quality.  Delay in arrival to start of treatment improved 47%. No change to wait for assessment or treatment.  Potential for confounding. Observer bias. No randomisation, lack of controlled design.  Grey literature consideration The NHS is arguably the first and largest healthcare organisation to adopt Lean into practice on a whole-scale manner [19]. However, the final report for PW contains piecemeal quantitative data to reinforce overall efficacy and sustainability [19] and was commissioned by the same division that devised the initiative creating risk of favourable reporting of outcomes [23]. Method of recruitment to the final report is not auditable and confounding is not addressed [19] which leads some of the outcomes to be vulnerable to misinterpretation; an issue inherent in QI measurement in healthcare in general [46]. A systematic review of PW (included in this study) mainly discovered experiential literature and states that few negative reports of PW have been published suggesting this highlights publication bias [23]. Grey literature has not been included in this study to avert risk of including any literature that may be ‘incomplete, biased and distorted’ [27: p.225]. Data extraction Owing to the inclusion of a number of different designs and there being no stand-alone, validated critical appraisal tool for this methodology [47], the Critical Appraisal Tool for Mixed-Methodology Integrative Review (CATMIR) was developed for the purposes of this study. CATMIR is based upon existing and validated critical appraisal tools (AMSTAR [44]; JBI Database Tools [48] and CASP [45]) (seeAppendix A). It was not possible to complete (pooled) meta-analysis as there were either sufficient data or the data were measured in different manners (see Table 2). Table 2 Waiting times and list volume pre- and post-lean intervention Study  Measure  Lodge and Bamford [50]  Modal wait for diagnostics scan (weeks)  Yousri et al. [68]  Volume of patients with door to theatre time in 24 h  McCulloch et al. [52]  Frequency of patients experiencing delay in access to treatment/investigation  Radnor [54]  Use of data within one intervention to reduce diagnostic waiting time (no values given)  Siddique et al. [67]  Mean waiting time for surgery (weeks)  Martin et al. [56]  Volume of hours waiting for radiology scan for diagnostics  Rushton et al. [51]  Volume of minutes for treatment duration and wait for treatment to commence  Study  Measure  Lodge and Bamford [50]  Modal wait for diagnostics scan (weeks)  Yousri et al. [68]  Volume of patients with door to theatre time in 24 h  McCulloch et al. [52]  Frequency of patients experiencing delay in access to treatment/investigation  Radnor [54]  Use of data within one intervention to reduce diagnostic waiting time (no values given)  Siddique et al. [67]  Mean waiting time for surgery (weeks)  Martin et al. [56]  Volume of hours waiting for radiology scan for diagnostics  Rushton et al. [51]  Volume of minutes for treatment duration and wait for treatment to commence  Table 2 Waiting times and list volume pre- and post-lean intervention Study  Measure  Lodge and Bamford [50]  Modal wait for diagnostics scan (weeks)  Yousri et al. [68]  Volume of patients with door to theatre time in 24 h  McCulloch et al. [52]  Frequency of patients experiencing delay in access to treatment/investigation  Radnor [54]  Use of data within one intervention to reduce diagnostic waiting time (no values given)  Siddique et al. [67]  Mean waiting time for surgery (weeks)  Martin et al. [56]  Volume of hours waiting for radiology scan for diagnostics  Rushton et al. [51]  Volume of minutes for treatment duration and wait for treatment to commence  Study  Measure  Lodge and Bamford [50]  Modal wait for diagnostics scan (weeks)  Yousri et al. [68]  Volume of patients with door to theatre time in 24 h  McCulloch et al. [52]  Frequency of patients experiencing delay in access to treatment/investigation  Radnor [54]  Use of data within one intervention to reduce diagnostic waiting time (no values given)  Siddique et al. [67]  Mean waiting time for surgery (weeks)  Martin et al. [56]  Volume of hours waiting for radiology scan for diagnostics  Rushton et al. [51]  Volume of minutes for treatment duration and wait for treatment to commence  Meta-narrative analysis of the literature was completed by first coding and identifying repeated occurrences/patterns in the data using the thematic analysis model suggested by Braun and Clarke [49]. This was then combined with Greenhalgh et al.’s [42] model where ‘storylines’ were identified across the chronology of the literature. Results of data synthesis Critical appraisal Studies achieved a mean CATMIR score of 8.5 (out of 14), with a range of 8 and standard deviation of 2.76. Studies that were more scientific in design (quasi-experimental and systematic review) tended to score more favourably over content analysis, action research and commissioned, peer-reviewed reports (seeAppendix B: CATMIR Matrix). Only one study used a robust experimental design—systematic review [23]. There was also a lack of awareness of confounding across the studies—observers and participants were largely aware of the hypothesis. Two experimental studies introduced new technology as opposed to using existing tools meaning outcome measures could be confounded [50, 51]. One quasi-experimental, interrupted time series study claimed that the Hawthorne effect was unavoidable in their design [52] (studies on the Hawthorne plant of the Western Electric Company, USA noticed behaviour modification in participants (increased productivity) occurred due to the sole act of participation where no intervention was implemented [53]). The secondary research did not consult failed implementations or non-adopters, therefore neutral (control) and/or negative views/figures are absent from the analyses. Sustainability Six of the studies addressed sustainability but only three measured it (by re-testing the data/hypothesis at a later date), two achieved success [50, 51]; the other (a systematic review) [23] gave meta-narrative analysis and largely found a lack of sustainability across the included literature (seeAppendix C—Sustainability Matrix). Experimental designs One study concerning a radiology waiting list redesign asserted correlation between staff perception and sustainability although gave no data to support this [50]. A study on safety and compliance in surgery tested sustainability of one issue (correct deep vein thrombosis (DVT) prophylaxis). Correct DVT prophylaxis rose from 35% (n = 161) pre-intervention to 87% (n = 157) post-intervention and marginally fell over the year (to ~80%) indicating sustained results [52]. Finally, a study concerning waiting and treatment times in a photopheresis unit measured sustainability of the intervention by re-testing the delay between a patient’s arrival and commencement of treatment. There was a fall from 66% to 48% of patients needing to wait over 15 min for treatment; the data were taken pre-intervention and 2 months following intervention although the intervention was simplistic and procedural [51]. Secondary research One large study of routine data and stakeholder interviews asserted that Lean is not a short-term remedy but a longitudinal change of culture [54]. One of the two included NHS Institute commissioned reviews of PW mentioned the importance of the receiving practice culture and system-readiness [21]. Finally, a systematic review of PW offered a narrative review on sustainability; that whole-service adoption is key but that the appetite for Lean may be dwindling due to ‘change fatigue’ [23: p.1368]. Heterogeneity and divergent approaches Adoption and implementation Generally, there were divergent methods of Lean adoption across the studies (seeAppendix D); the most widely used was value-stream/process mapping. Most studies used two distinct aspects of Lean (mode = 2) although one study used six (and achieved the highest CATMIR score) [52]. Four studies concerned the adoption of PW [21, 23, 27, 54]. Study designs Most quasi-experimental studies used an interrupted time series design, one combined this with action research [50], and another incorporated failure mode and effects analysis [55]. One mixed-methods study combined this design with qualitative research [56]. The secondary literature was more diverse where four studies adopted mixed-methods: a large, multi-site study used three case studies [54]; two national studies on PW used routine data, stakeholder interviews and hospital case studies [21, 57]; and another nationwide study conducted content analysis of all annual reports published by NHS organisations [27]. One systematic review of PW largely concerned the UK implementation and was the only included study with a scientifically rigorous design [23]. Outcome measures There were 22 different outcomes measured across the studies; the most common being waiting times with five discovering improvement with statistical evidence and three without. There was further diversity within the outcome measures; these were undertaken in different ways and with different values (see Table 2). Owing to lack of uniformity of measurement in the data, it was not possible to complete meta-analysis. A study testing safety process compliance in surgery did not subject two of the processes to the Lean intervention (PDCA—plan, do, check, act). This led to marginal changes in compliance rates where there were much greater increases in compliance in the outcomes that were subject to PDCA [52]. Discussion The results of this review indicate that there are many competing factors in the study of QI and Lean which contribute to an overall difficulty in achieving clarity. Quality of healthcare cannot be measured and sustained unless it is first defined [58]. Yet definition has proven to be fluid and adaptable; it is malleable depending on economic and political factors [59]. Lean is designed to determine and address intrinsic value yet there are heterogeneous, divergent and global definitions of value [24, 34]. This contributes to variety in the manner of adoption and subsequent diverse study design and measurement. Ambiguity in definition and implementation have contributed to the erosion of a system-wide Lean implementation in an NHS acute trust and formed the focus of a large ethnographic study [29]. Uncertainty and divergence also creates difficulty in achieving a meta-analytical/narrative view. There is also a widely-held view that Lean has been diluted, implemented narrowly and reserved for designated problem areas or specific units [28, 60]. Secondary research has highlighted that favourable results have been lauded and negative experiences under-reported [23, 39]. Critics of Lean assert that ‘healthcare is not directly comparable to manufacturing’ [39: p.134] and cite the differences in influence to output volume between the two; general economic and product demand, respectively. Part of Lean’s popularity amongst organisations is the appeal of continuous QI [10] although many have struggled to sustain results in the medium- to longer-term [61]. Paradoxically, ‘kaizen’ forms a central part of the ideology [62] making it difficult to understand why sustainability is not achieved widely. A common assertion is that success and sustainment of QI is reliant on the recipient culture [35]. However, a systematic review of the diffusion of innovations in the UK health service asserted that definition and measurement of recipient culture is diverse, and that the whole process of examining and measuring QI requires uniformity [63]. The study calls for increase in robust, empirical designs which are otherwise absent [63]. There is also no blueprint to guide the introduction of QI in complex organisations [36]. Plotting the literature in this study over a timeline reveals an evolution from pragmatic (quasi-scientific and experiential) research to more academic and scientific designs. Yet, there continues to be a lack of robust methodological quality which leaves studies vulnerable to problems with internal validity. There are also difficulties as a result of participant observation (where there is greater measured compliance with overt observers in studies on safety) and also where all parties are aware of the hypothesis [64]. The Hawthorne effect has also been seen as an opportunity to improve safety compliance without necessarily implementing anything new or complex [65]. Yet, a safety compliance study [52] did not expose one set of outcome measures to Lean intervention and only achieved marginal results in comparison to greater compliance in PDCA groups. However, safety and compliance have also been positively influenced by interventions that focus on teamwork and culture change alone [66]. Although most studies were not clouded by the introduction of new technology, there remain issues with participant and observer knowledge of hypothesis and/or lack of randomisation in recruitment [51, 55, 67]. The secondary research was generally not inclusive of non-adopting organisations or failed interventions suggesting positive bias in recruitment and therefore publication. Strengths and limitations of the study This is the first literature review of Lean in the NHS that has not been restricted to PW and also included experimental and non-experimental literature. By doing so, it has allowed for consideration of the qualitative aspects of the intervention, statistical analysis and awareness of trends in adoption and implementation. Limitations of this study are the lack of inclusion of grey literature (and theoretical works), wider qualitative research (e.g. aspects of adoption such as staff/patient perceptions completed in single-methods research) and international literature. Hand-searching of printed literature was also not completed. There is a valid debate as to whether a scientific model is appropriate for analysis of Lean given the complexity of studying QI and working-cultures. Although the internal validity of this study is robust, CATMIR tended to score more positively on experimental designs indicating that the tool may require further refinement. Conclusion It continues to be difficult to give an overall conclusion on Lean’s efficacy and sustainability owing to flaws in methodological design leading to uncertainty in results. This review concurs with other evidence citing that there is heterogeneity in definition and divergence in translation to practice alongside the risk of confounding and publication bias [23, 29, 54, 60]. Despite pockets of positive results, the available evidence does not support an overall claim for sustainability of the ideology without other potential confounding issues. More rigorous and controlled designs including a qualitative dimension, particularly with regard to the recipient culture, are needed to be able to form an omniscient view of Lean and its sustainability in today’s NHS. 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International Journal for Quality in Health CareOxford University Press

Published: Apr 10, 2018

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