Background: The aim of this study was to examine whether work capabilities differ between workers with Multiple Sclerosis (MS) and workers from the general population. The second aim was to investigate whether the capability set was related to work and health outcomes. Methods: A total of 163 workers with MS from the MS@Work study and 163 workers from the general population were matched for gender, age, educational level and working hours. All participants completed online questionnaires on demographics, health and work functioning. The Capability Set for Work Questionnaire was used to explore whether a set of seven work values is considered valuable (A), is enabled in the work context (B), and can be achieved by the individual (C). When all three criteria are met a work value can be considered part of the individual’s ‘capability set’. Results: Group differences and relationships with work and health outcomes were examined. Despite lower physical work functioning (U = 4250, p = 0.001), lower work ability (U = 10591, p = 0.006) and worse self-reported health (U = 9091, p ≤ 0.001) workers with MS had a larger capability set (U = 9649, p ≤ 0.001) than the general population. In workers with MS, a larger capability set was associated with better flexible work functioning (r = 0.30), work ability (r = 0.25), self-rated health (r = 0.25); and with less absenteeism (r = − 0.26), presenteeism (r = − 0.31), cognitive/neuropsychiatric impairment (r = − 0.35), depression (r = − 0.43), anxiety (r = − 0.31) and fatigue (r = − 0.34). Conclusions: Workers with MS have a larger capability set than workers from the general population. In workers with MS a larger capability set was associated with better work and health outcomes. Trial registration: This observational study is registered under NL43098.008.12: ‘Voorspellers van arbeidsparticipatie bij mensen met relapsing-remitting Multiple Sclerose’. The study is registered at the Dutch CCMO register (https://www.toetsingonline.nl). This study is approved by the METC Brabant, 12 February 2014. st First participants are enrolled 1 of March 2014. Keywords: Multiple sclerosis, Work, Sustainable employability, Capability set for work, Health * Correspondence: email@example.com National Multiple Sclerosis Foundation, Mathenesserlaan 378, Rotterdam 3023 HB, The Netherlands Department of Psychology, Section Health, Medical and Neuropsychology, Leiden University, PO Box 9555, Leiden 2300 RB, The Netherlands Full list of author information is available at the end of the article © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. van Gorp et al. Health and Quality of Life Outcomes (2018) 16:113 Page 2 of 11 Background and performance. Consequently, seven work values were Work participation is important from both a societal identified: (i) use of knowledge and skills, (ii) develop- and personal perspective. In many European countries ment of knowledge and skills, (iii) involvement in im- greater and prolonged work participation is necessary to portant decisions, (iv) building and maintaining meet the economic and social demands of an aging soci- meaningful contacts at work, (v) setting your own goals, ety [1, 2]. This means that it is important to invest in (vi) having a good income and (vii) contributing to keeping both ageing and disabled workers engaged with something valuable . A new instrument was devel- the labour market. From a personal perspective, work of- oped based on Van der Klink’s model of sustainable em- fers not only financial benefits, but also the ability to use ployability, the ‘Capability Set for Work Questionnaire’. knowledge and skills and to have meaningful contacts This questionnaire represents an operationalization of with others [3, 4]. the ‘capability set’ [3, 10]. The questionnaire explores Multiple Sclerosis (MS) is a chronic disorder of the whether the set of seven work values are considered central nervous system, often diagnosed in young or valuable by the worker (A), are enabled in the work con- middle adulthood. MS is characterized by a wide range text (B), and can be achieved (C). An individual work of symptoms, including disturbances in motor, visual, value is considered part of the ‘capability set’ of an indi- sensory, autonomic systems and fatigue . Work par- vidual worker when it is considered important (A), and ticipation is compromised when an individual has MS. the workplace offers the opportunity to achieve the value Previous research showed that work participation de- (B), and the worker is able to achieve the value (C). A creased from 75 to 80% in the early stages of the disease larger capability set was associated with better work (Expanded Disability Status Scale (EDSS): 0–1) to less functioning in a general working population . than 5% in the very late stages of the disease (EDSS: 7–9) Employment research in MS has had a large focus on . Job sustainability was found to be influenced by many demographic and disease-related factors while little evi- different factors, including MS symptoms, financial and dence exists on the influence of the work context  personal considerations, attitudes towards work and the and one’s personal view of the importance of work and workplace environment . Personal considerations and what one perceives as valued aspects of work. Research attitudes towards work that stimulate job retention in- on the mutual influence of MS and the conditions ne- cluded, among others, ‘being interested in your work’, ‘be- cessary for sustainable employability may help to better ing motivated’, ‘social interaction’ and ‘certainty about your understand how to create an optimal situation so that capabilities’ . The complexity of the costs and benefits workers with MS remain engaged in the labour market. of work must be taken into account as a balance between The first aim of the current study was to examine work and other aspects in life is of great importance . It whether the capability set and work values of workers with should be noted that life outside work is also an important MS differed from matched peers in terms of importance, determinant of sustainable employability . enablement and achievement. Additionally, discrepancies It seems that in order to stimulate work participation between importance, opportunities and achievement in patients with MS, people should perceive their daily within the individual work values were examined explor- work as a valuable part of life and not as a burden. atively. The second aim was to investigate whether the Van der Klink et al.  recently developed a model of capability set was related to work-related and health out- sustainable employability based on Sen’s capability ap- comes. We expected that due to compromised health in proach . The following definition of sustainable em- workers with MS, work values cannot be achieved as eas- ployability was formulated; ‘sustainable employability ily as in workers from the general population, which in means that throughout their working lives, workers can turn would lead to a smaller capability set in workers with realize tangible opportunities in the form of a set of cap- MS. Additionally, we expected to find conflicts between abilities. They also enjoy the necessary conditions that the importance, opportunities and actual achievement of allow them to make a valuable contribution through work values in workers with MS. Furthermore, we ex- their work, now and in the future, while safeguarding pected to find relations between a larger capability set and their health and welfare. This requires on the one hand better work and health outcomes. a work context that facilitates them, and on the other hand the attitude and motivation to exploit these oppor- Methods tunities’. In this definition a set of capabilities refers to Design valued aspects of work that workers are both enabled A cross-sectional study design was used. and able to achieve. Theoretically, having a larger capability set is linked to Participants better quality of working life and the achievement of Three hundred eight patients with MS were recruited in valuable functioning, e.g. better work ability, engagement the context of the MS@Work study via MS outpatient van Gorp et al. Health and Quality of Life Outcomes (2018) 16:113 Page 3 of 11 clinics in the Netherlands . Inclusion criteria for the the ‘capability set’ derived from the model of sustainable current study were (a) a diagnosis of relapsing-remitting employability [3, 10]. The questionnaire explores MS (RRMS) according to the Polman-McDonald criteria whether a set of seven valued work aspects, are consid- 2010 , (b) 18 years and older, (c) currently having a ered valuable by the worker (A), are enabled in the work paid job (d) completing the ‘Capability Set for Work context (B), and can be achieved (C). In relation to each Questionnaire’. Patients with co-morbid psychiatric or of these seven valued work aspects the worker is asked neurological disorders, substance abuse, neurological im- (A) ‘How important is <the value> for you?’ (B) ‘Does pairment that might interfere with cognitive testing or your work offer the opportunities to achieve <the value>’ unable to speak and/or read Dutch were excluded from and (C) ‘To what extent do you actually achieve <the the study. Five patients were excluded because of an un- value>?’ on a scale from 0 = ‘definitely not’ to 5 = ‘very clear diagnosis. A total of 72 patients with MS did not much’. An individual value is considered part of the have a paid job. Another 68 workers with MS did not re- capability set of an individual worker when it is consid- ceive the Capability Set for Work Questionnaire, because ered important (A) (score 4–5), and the workplace offers the questionnaire was added at a latter point in time to the opportunity to achieve the value (B) (score 4–5), and the MS@Work study. This led to the inclusion of 163 the worker is able to achieve the value (C) (score 4–5). workers with MS (77% females; median age 43.0, ranging The capability set can therefore encompass up to seven from 24 to 64 years old). The group of 68 workers with values. An overall question for the capability for work MS who were excluded due to missing Capability Set for was posed: ‘Taking all things together, I think I have Work Questionnaire-data did not differ in terms of age, enough opportunities to remain working’, which required gender, educational level, disability level, disease dur- a response ranging from 1 = ‘totally disagree’ to 5 = ‘ ation and work hours. totally agree’. All workers with MS completed online questionnaires Education level was in both groups classified based on on work functioning and MS symptoms, and underwent the Dutch classification system, according to Verhage et neuropsychological and neurological examinations al. . Education level was divided into three levels; (methods and data to be reported elsewhere). We used low, middle or high education. People were considered data from a large survey study meant to evaluate the con- to have a low level of education up to finishing low level struct validity of the Capability Set for Work Questionnaire secondary school. Middle education corresponds with . The validation study used a panel agency to approach finishing secondary school at a medium level. People a representativesample(N = 1250) of the Dutch general were considered highly educated when they finished working population. In the current study we included 163 secondary school at the highest level and/or obtained a Dutch workers matched for gender, age, level of education college or university degree. and working hours. More details about the survey study Work ability was in both groups examined using the can be found in Abma et al. . item ‘current work ability compared with the lifetime best’ of the Work Ability Index (WAI) . Possible scores Ethical approval range from 0 = ‘completely unable to work’ to 10 = ‘work The MS@Work study was approved by the Medical ability at its best’. The use of a single item of the WAI has Ethical Committee Brabant (NL43098.008.12 1307) and been shown to be valid and simple indicator of work the Board of Directors of the participating MS out- ability . patient clinics. All subjects provided written informed Work functioning was examined in both groups with consent. For the panel study no ethical approval was ne- two subscales from the Work Role Functioning cessary according to the medical ethics committee of the Questionnaire 2.0 (Dutch Version) (WRFQ 2.0) : University Medical Centre Groningen as it did not qual- physical and flexibility demands. The WRFQ 2.0 mea- ify for being tested according to the Dutch Medical sures the perceived percentage of time that physical and Research Involving Human Subjects act of 1998 . emotional problems impact certain work demands. The panel study was performed according to the Scores range from 0 to 100, with higher scores indicat- guidelines of the Association of Universities in the ing better work functioning. Netherlands . Participants provided online informed Self-rated health was measured in both groups with a consent . Both studies were performed in agreement question from the Short Form-12 : ‘In general, how with the Declaration of Helsinki . would you rate your health?’. Response categories ranged from 1 (very good) to 5 (very poor), which were recoded Measures in a way that a higher score represent a better self-rated Work capabilities were examined using the Capability health. Set for Work Questionnaire (CSWQ) in both groups. Working hours was measured in hours per week in This questionnaire represents an operationalization of both groups. van Gorp et al. Health and Quality of Life Outcomes (2018) 16:113 Page 4 of 11 Absenteeism was measured using number of days ab- This scale assesses the impact of fatigue on daily func- sent from sickness in the past 3 months (in the general tioning in physical, cognitive, and psychosocial dimen- working population) or the number of days absent from sions. Possible total scores range from 0 to 84. Total work in the past year (in workers with MS). In workers scores at or above 38 are considered indicative of with MS absenteeism was measured on an ordinal scale. MS-related fatigue . 0 days, 1–3 days, 4–5 days, 6–10 days, 11–20 days, 20 days – 6 weeks, 7–13 weeks, 3–6 months, 6 months- Statistical analysis 1 year, or not applicable. It was not possible to compare SPSS for Windows (release 23.0) was used for data ana- this variable between groups, due to the use of different lysis. Workers from the general population were scales. We did look at correlations between the capabil- matched with workers with MS using fuzzy case-control ity set and the separate measures of absenteeism. matching for gender (tolerance = 0), age (tolerance = 8), Presenteeism was measured only in workers with MS working hours (tolerance = 5) and level of education (tol- and represents the self-reported influence of MS symp- erance = 1). Differences in demographics, self-rated toms on work productivity on a scale from 1 to 10 in health, work ability, work functioning and capability as- which higher scores represent more influence of the MS pects between workers with MS and the general working symptoms on work productivity. This question is part of population were analysed using parametric or the Work Productivity and Activity Impairment non-parametric tests. Additionally, using Wilcoxon Questionnaire . Signed Rank Tests, we examined discrepancies between Disability level in workers with MS was quantified the importance of each value (A), whether the value was using the Expanded Disability Status Scale (EDSS) . enabled (B) and whether the person was able to achieve Scores range from 0 (normal neurological exam) to 10 the value (C), but only for important values (score 4–5). (death due to MS) and increment with steps of 0.5. The Spearman’s rho correlation analyses were performed to EDSS was assessed by a neurologist during the neuro- examine whether the capability set and overall capability logical examination (as part of the MS@Work study) at item were related to measures of work functioning and the outpatient clinic where the patient with MS is being health. Correlation coefficients between 0.15–0.29 were treated. Scores between 0 and 3.5 represent mild disabil- interpreted as weak, 0.3–0.59 were interpreted as mod- ity, 4.0–6.5 represent moderate disability and scores of erate and 0.6–1 were interpreted as strong . To cor- 7.0 and above are seen as a severe level of disability . rect for multiple testing a Bonferroni correction was Cognitive and neuropsychiatric functioning was mea- used for the interpretation of statistical significance. Due sured in workers with MS using the Multiple Sclerosis to the exploratory nature of the analyses for discrepan- Neuropsychological Screening Questionnaire (MSNQ) cies between A, B and C, a p value of 0.01 was consid- . Scores range from 0 to 60 and higher scores are in- ered trend significant. dicative of greater subjective cognitive and neuropsychi- atric impairment. Information processing speed was examined using the Results Symbol Digit Modalities Test (SDMT)  in workers Demographics, work and self-reported health with MS. The SDMT was administered by a trained re- The MS sample and the matched group included espe- search nurse or (neuro)psychologist during a cognitive cially females (77%) in their early 40’s(see Table 1). The examination (as part of the MS@Work study) at the out- majority of workers with MS were employed in office and patient clinic where the patient with MS is being treated. administrative support (22%), the healthcare sector (15%), The SDMT is often used as an indicator of cognitive education, training and library (9%) and business and fi- functioning in MS . Possible total scores range from nancial services (8%). The majority of workers from the 0 to 110. Higher scores indicate better performance. general population were employed in the healthcare sector Z-scores were retrieved from the SDMT manual, (26%), education (7%), the retail industry (7%) and other Z-scores below − 1,5 were considered indicative for an business services (7%) (note; in 17% type of work was re- impairment in information processing speed . ported as ‘other’ and not further specified). The majority Anxiety and depression were examined in workers with of workers with MS reported 1–3 days absent (27%), 0 days MS using the Hospital Anxiety and Depression Scale (24%) and 4–5 sick days (16%) in the past year. In the (HADS) . Possible scores per domain, i.e. anxiety or general population the median days called in sick was 0 depression, range from 0 to 21 and scores at or above 8 (IQR = 0), with 76.5% of the general population reporting are considered indicative of major depression or general- no absenteeism in the past 3 months. ized anxiety disorder as validated in MS . The data on demographics, self-rated health, work abil- Fatigue impact was measured in workers with MS ity and work functioning in workers with MS and workers using the Modified Fatigue Impact Scale (MFIS) . from the general population are presented in Table 1. van Gorp et al. Health and Quality of Life Outcomes (2018) 16:113 Page 5 of 11 Table 1 Demographic, self-rated health, work ability and work functioning findings in workers with MS and workers from the general population Workers with MS (N = 163) General working population (N = 163) Test statistics % Mean Median IQR Min - max % Mean Median IQR Min-Max X U p Gender (female) (in %) 77.3% 76.7% 0.17 0.89 Age 42.5 43.0 15.0 24–64 42.5 44.0 16.0 19–67 13163.0 0.89 Educational level 3.07 0.22 Low (%) 14.1% 14.7% Medium (%) 41.7% 50.3% High (%) 44.2% 35.0% a * Self-rated health (scale 1–5) 2.9 3.0 1.0 1–5 3.4 3.0 1.0 2–5 9091.0 < 0.001 Number of work hours per week 29.1 30.0 17.0 6–60 29.9 30.0 16.0 5–60 12520.5 0.37 a * Work ability (scale 0–10) 7.1 8.0 2.0 0–10 7.7 8.0 2.0 0–10 10590.5 0.006 a * Work Functioning Physical (scale 0–100) 77.4 90.0 35.6 0–100 89.9 100.0 15.0 25–100 4250.0 0.001 Work Functioning Flexibility (scale 0–100) 75.3 85.0 25.0 0–100 81.3 87.5 20.8 16.7–100 10425.0 0.46 Note: IQR Inter Quartile Range. Although all data are non-parametric, mean scores are displayed to further clarify the distribution of the data Higher scores indicate better self-rated health, work ability, and work functioning Bonferroni corrected p values ≤ 0.006 were considered significant There were no group differences in gender, age, educa- In the group of workers from the general population tional level, number of work hours or work functioning in 26.4% reported having a chronic disease, ranging from terms of flexibility. In both groups, males worked signifi- problems with the human musculoskeletal system cantly more hours than females. Work hours were equally (17.2%; e.g. rheumatoid arthritis) to respiratory tract dis- distributed based on educational level, and age within and orders (8.0%; e.g. Chronic Obstructive Pulmonary between both groups. Workers with MS rated their health, Disease). work ability, and physical work functioning lower than workers from the general population (Table 1). Disease Work capabilities characteristics of workers with MS are shown in Table 2. A comparison of work capabilities in workers with A total of 91.5% of the workers with MS had a mild dis- MS and workers from the general population is pre- ability level (EDSS:0–3.5) and 8.5% had a moderate dis- sented in Table 3. Many work values were rated as ability level (EDSS:4.0–6.5). A total of 73% of the workers more important (A), more enabled in the work con- with MS received Disease Modifying Treatment (DMT). text (B) and more able to achieve (C) by workers Based on the scores on the SDMT 2.5% of the workers with MS than workers from the general working with MS had an impairment in information processing population. Overall, workers with MS had a larger speed. Within workers with MS, 11.7% reported scores in- capability set, and had a greater belief in sufficient dicative for a major depression, and 25.2% reported scores opportunities to continue working as measured with indicative for a general anxiety disorder. Scores indicating the overall item of the CSWQ. Within each group, the presence of MS-related fatigue were reported by the value ‘use of knowledge and skills’ (in 85 and 42.3% of the workers with MS. 67% respectively) and ‘building and maintaining Table 2 Disease characteristics of workers with MS Workers with MS (N = 163) Median IQR Mean SD Min-Max Disability level (1–10) 2.0 1.0 0–6 Disease duration (in years) 6.0 10.0 0–31 Depression (0–21) 2.0 4.0 0–14 Anxiety (0–21) 5.0 5.0 0–21 Fatigue Impact (0–84) 33.7 15.4 0–73 Cognitive and neuropsychiatric functioning (0–61) 19.0 12.0 1–51 Information processing speed (0–110) 53.9 8.3 31–75 Note: IQR Inter Quartile Range, SD Standard Deviation van Gorp et al. Health and Quality of Life Outcomes (2018) 16:113 Page 6 of 11 Table 3 Comparison of work capabilities between workers with MS and workers from the general population Workers with MS (N = 163) General working population (N = 163) Test statistics Work capabilities % Mean Median IQR Min-max % Mean Median IQR Min-max X U p i. Use of knowledge and skills in your work A. Importance 4.6 5.0 1 3–5 4.3 4.0 1 2–5 9823.0 < 0.001 B. Opportunities 4.4 4.0 1 2–5 3.8 4.0 0 1–5 22062.0 < 0.001 C. Able to achieve 4.3 4.0 1 1–5 3.9 4.0 1 1–5 23190.0 < 0.001 Included in capability set (in %) 85% 67% 14.9 < 0.001 ii. Development of knowledge and skills in your work A. Importance 4.2 4.0 1 1–5 4.1 4.0 1 1–5 11637.5 0.42 B. Opportunities 3.9 4.0 0 1–5 3.5 4.0 1 1–5 9802.5 < 0.001 C. Able to achieve 3.7 4.0 1 1–5 3.4 4.0 1 1–5 11511.0 0.33 Included in capability set (in %) 57% 49% 2.6 0.11 iii. Involvement in important decisions A. Importance 4.3 4.0 1 2–5 3.8 4.0 0 1–5 9066.5 < 0.001 B. Opportunities 3.9 4.0 2 2–5 3.3 3.0 1 1–5 8654.5 < 0.001 C. Able to achieve 3.8 4.0 1 2–5 3.3 3.0 1 1–5 9136.5 < 0.001 Included in capability set (in %) 61% 39% 15.9 < 0.001 iv. Building and maintaining meaningful contacts at work A. Importance 4.4 4.0 1 1–5 4.1 4.0 1 2–5 10541.5 < 0.001 B. Opportunities 4.2 4.0 1 1–5 3.9 4.0 0 1–5 10433.0 < 0.001 C. Able to achieve 4.1 4.0 1 1–5 3.8 4.0 1 2–5 10759.0 0.001 Included in capability set (in %) 82% 68% 8.7 0.003 v. Setting your own goals in your work A. Importance 4.1 4.0 1 2–5 3.9 4.0 1 1–5 10734.0 0.005 B. Opportunities 3.9 4.0 1 2–5 3.6 4.0 1 1–5 10827.0 0.007 C. Able to achieve 3.8 4.0 1 2–5 3.6 4.0 1 1–5 11152.0 0.03 Included in capability set (in %) 63% 54% 2.5 0.11 vi. Having a good income A. Importance 4.1 4.0 1 1–5 4.0 4.0 0 2–5 12105.0 0.41 B. Opportunities 3.9 4.0 1 2–5 3.3 3.0 1 1–5 8276.5 < 0.001 C. Able to achieve 3.8 4.0 1 2–5 3.2 3.0 1 1–5 8092.0 < 0.001 Included in capability set (in %) 62% 39% 16.7 < 0.001 vii. Contributing to something valuable in your work A. Importance 4.3 4.0 1 3–5 4.0 4.0 1 1–5 9733.5 < 0.001 B. Opportunities 4.1 4.0 1 2–5 3.6 4.0 1 1–5 8467.5 < 0.001 C. Able to achieve 3.9 4.0 2 2–5 3.6 4.0 1 1–5 9660.0 < 0.001 Included in capability set (in %) 71% 54% 9.1 0.002 Capability set 4.8 5.0 3 0–7 3.7 4.0 4 0–7 9649.0 < 0.001 Overall item: Altogether, I think I have 4.3 4.0 1 2–5 3.8 4.0 0 1–5 8476.0 < 0.001 sufficient opportunities to continue to work. Note: IQR Inter Quartile Range. Although all data are non-parametric, mean scores are displayed to further clarify the distribution of the data Bonferroni corrected p values ≤ 0.002 were considered significant meaningful contacts at work’ (in 82 and 62% respect- income’ and ‘contributing to something value’ were ively) were most often included in the capability set. more often included in the capability set by workers The work values ‘use of knowledge and skills’, ‘in- with MS than in the capability set of workers from volvement in important decisions’, ‘having a good the general population. van Gorp et al. Health and Quality of Life Outcomes (2018) 16:113 Page 7 of 11 Differences between the importance (A), being enabled work value, and being enabled and actually being able to (B) and being able to achieve (C) work values achieve the work value. Only in workers with MS, a dis- Within each group we found significant discrepancies be- crepancy between being enabled and actually being able to tween the importance of a value (A) that was considered achieve a work value was found. In workers with MS a lar- important (score 4–5) and whether the person was en- ger capability set was weakly to moderately associated abled (B) and able to achieve (C) the value (Table 4). In with better work and health outcomes. both groups, for every work value the importance (A) was considered higher than being enabled in the work context Importance of values and opportunities at work (B) and being able to achieve (C) the work value. Workers with MS on average rate each work value as Discrepancies between being enabled (B) and actually important to very important. In fact, workers with MS being able to achieve (C) the value were only found within find it significantly more important than workers from workers with MS. Discrepancies were found in two of the the general population to be able to use knowledge and seven values; ‘development of knowledge and skills’ and skills, to be involved in important decisions at work, to ‘contributing to something valuable’.In four valuestrend build and maintain meaningful contacts at work and to significant discrepancies were found between being en- contribute to something valuable. abled (B) and actually being able to achieve (C). In all Having a chronic, inflammatory and neurodegenera- these values workers with MS rated the opportunities at tive illness like MS may stimulate rethinking and in- work higher than the extent to which they were able to creases awareness of the importance of having a job, and achieve these values. what aspects make work important. This idea fits well in the Shifting Perspectives Model of Chronic Illness, Associations between work capabilities, work and health which proposes that a person living with a chronic dis- outcomes ease continually goes through shifts in perspective from Associations between work capabilities and work and either ‘illness in the foreground’ to ‘wellness in the fore- health outcomes are presented in Table 5. Weak to moder- ground’ . When the wellness perspective comes to ate associations were found between a larger capability and the foreground, the focus shifts to the self instead of the a larger overall capability item and better work and health diseased body, which may lead to a re-appreciation of outcomes in workers with MS. In the general population a life and others, including situations (e.g. work) affected larger capability set and a larger overall capability item were by the disease. On the other hand, when the focus shifts weakly to moderately associated with better work ability. to the illness, the world around them may receive less attention. The Shifting Perspectives Model assumes that Discussion a person with a chronic disease has one preferred per- We observed that workers with MS have a larger capabil- spective and that no perspective is better or worse than ity set than workers from the general population. In both the other. Considering the high importance the workers groups we found conflicts between the importance of each with MS place on work values, the prevalent perspective Table 4 Discrepancies between the importance (A), being enabled (B) and being able to achieve (C) work values in workers with MS and workers from the general population Workers with MS (N = 163) General working population (N = 163) a a a a a a Capability aspects (A-B) (A-C) (B-C) (A-B) (A-C) (B-C) Z p Z p Z p Z p Z p Z p ** ** * ** ** i. Use of knowledge and skills in your work −5.2 < 0.001 − 5.6 < 0.001 − 2.5 0.009 − 6.2 < 0.001 − 6.0 < 0.001 − 0.8 0.40 ** ** ** ** ** ii. Development of knowledge and skills in your − < 0.001 − 7.3 < 0.001 − 4.2 < 0.001 −6.9 < 0.001 − 7.1 < 0.001 − 0.2 0.85 work 5.5 ** ** * ** ** iii. Involvement in important decisions −6.7 < 0.001 − 7.3 < 0.001 − 2.8 0.005 − 6.7 < 0.001 −7.1 < 0.001 − 0.5 0.59 ** ** * ** ** iv. Building and maintaining meaningful contacts −5.1 < 0.001 − 6.0 < 0.001 −2.6 0.008 −5.3 < 0.001 − 5.8 < 0.001 − 1.4 0.16 at work ** ** * ** ** v. Setting your own goals in your work −4.9 < 0.001 −5.7 < 0.001 −2.9 0.004 −5.2 < 0.001 −5.6 < 0.001 −1.7 0.09 ** ** ** ** vi. Having a good income −5.6 < 0.001 −5.7 < 0.001 −1.3 0.184 −7.6 < 0.001 −7.8 < 0.001 −1.9 0.05 ** ** ** ** ** vii. Contributing to something valuable in your −4.6 < 0.001 −6.1 < 0.001 − 4.5 < 0.001 − 6.3 < 0.001 −6.8 < 0.001 −1.2 0.22 work Note: Results of the Wilcoxon Signed Rank Test to test discrepancies between importance (A), being enabled (B) and being able to achieve (C) work values are presented Conflict scores ** * Bonferroni corrected p values ≤ 0.001 were considered significant, p values ≤ 0.01 were considered trend significant van Gorp et al. Health and Quality of Life Outcomes (2018) 16:113 Page 8 of 11 Table 5 Associations between work capabilities, work and health-related outcomes Workers with MS (N = 163) General working population (N = 163) Capability set Overall capability item Capability set Overall capability item Age −0.03 − 0.17 − 0.04 − 0.07 Work hours 0.19 0.29 0.21 0.16 * * * * Work ability 0.25 0.43 0.28 0.39 Work Functioning-Physical 0.19 0.39 0.22 0.19 * * Work Functioning-Flexibility 0.30 0.27 0.11 0.25 * * Absenteeism −0.26 −0.29 0.02 −0.02 * * Presenteeism −0.31 −0.42 n.a. n.a. * * Self-rated health 0.25 0.39 0.01 0.21 Disease duration 0.12 0.02 n.a. n.a. Disability level −0.05 −0.13 n.a. n.a. * * Cognitive and neuro-psychiatric functioning −0.35 −0.44 n.a. n.a. Information processing speed 0.05 0.09 n.a. n.a. * * Depression −0.43 −0.39 n.a. n.a. * * Anxiety −0.31 −0.38 n.a. n.a. * * Fatigue impact −0.34 −0.44 n.a. n.a. Note: Spearman’s rho coefficients are reported. Not all health measures were available for the general working population (n.a data not available) Bonferroni corrected p values ≤ 0.001 were considered significant in our sample may be ‘wellness in the foreground’.In functioning and declining health through an open and this respect, we should be aware that our sample may supportive climate at work and provision of sufficient not be generalizable to all workers with MS. Patients opportunities and possible accommodations. Disclos- with MS who do not find work participation that im- ure of disease status  may also lead to such an portant, may have left the labour market at an earlier environment. In the current study the vast majority stage. It is possible that the workers with MS in the (94%) of the workers with MS have disclosed their current study are characterized by a specific disease status to their supervisor. Messmer et al.  MS-phenotype. A selection bias may arise, in that people identified various workplace changes that facilitate with more positive personal expectations, a better bal- work participation for people with MS, including a ance between work and other aspects in life, lower dis- flexible work schedule, changes in tasks, increased ac- cessibility and time off when needed. In the workers ease severity and more motivation are over represented in our group of workers with MS, causing a possible with MS in the current study, 69.9% made some sort of work accommodation, ranging from an accommo- ‘healthy worker effect phenomenon’ . In addition, it dation in flexible work scheduling (50.9%; i.e. changed is possible that the participants in the panel study might have placed questions about work and work values into work hours, rest periods), to physical changes to sur- roundings (41.1%) and cognitive aids (35.6%; i.e. a different perspective. There may have been a higher memory aids or written work instructions). awareness of these work values in workers with MS, as they know and feel the importance as well as the precar- A possible explanation for the increased feeling of be- ing able and enabled to maintain valued aspects of work iousness of their employment. in workers with MS may lie in the fact that in the Workers with MS generally rate opportunities at current study many workers with MS were able to ar- work higher than workers from the general popula- range work accommodations in consultation with their tion, and feel better able to achieve most values. This supervisor. This positive experience of being facilitated is also reflected in a larger capability set and a higher might change a person’s attitude and sense of control to- score on the overall capability item in workers with wards work in a positive way . MS compared to workers from the general popula- tion. Nevertheless, workers with MS rate their phys- ical work functioning, work ability and self-rated Conflicts between the importance (A) and being enabled health lower than workers from the general popula- (B) and able to achieve (C) values tion. It is likely that workers with MS were able to In both groups, we found that the importance of valued compensate for their lower level of physical work work aspects, for all seven values, was rated higher than van Gorp et al. Health and Quality of Life Outcomes (2018) 16:113 Page 9 of 11 the extent to which the workplace offers opportunities illness, we cannot be sure if, how, and to what extend to achieve these values (A-B). Furthermore, the import- this has introduced bias in this study. In our study the ance of valued work aspects was rated higher than the expected associations between the CSWQ with health extent to which the workers were actually able to and work outcomes were replicated. Nonetheless, the achieve these values (A-C). Differences between being CSWQ would benefit from further validation. enabled and actually being able (B-C) to achieve valued A strength of the current study is that we were able work aspects were found within the workers with MS to carefully match the workers with MS to workers but not in the general population. from the general population based on gender, age, The data of the general population used in our study, level of education and work hours. The data on was part of a larger group of workers from the validation workers from the general population included workers study on the validation of the CSWQ , which similarly with a chronic disease. Although it could be discussed reported no differences between the B and C items. The that including workers with a chronic disease intro- assumption of Abma et al.  that in workers with differ- duces a bias, the sample provides a good representa- ences between B and C, something outside the work situ- tion of the general working population of which ation is hindering workers from succeeding in realizing workers with a chronic disease are also part. Previous the work capability, is credible given that these differences research shows that between 25 and 37% of all Dutch were only seen in workers with MS. The adverse health ef- workers are affected by a chronic disease [37, 38]. fects of MS, including fatigue, depression, anxiety and Due to the fact that both study populations are subtle decreases in physical functioning, seem to interfere retained from different studies a discrepancy occurred in with the possibility to actually achieve these work aspects the manner in which ‘absenteeism’ and ‘job type’ were even though opportunities are offered at work. measured. These measures could not be compared be- tween groups. Moreover, not all health measures that Associations between work capabilities, work functioning were available for the workers with MS were available and health for the workers from the general population. Having a larger capability set for work has been associ- A possible selection bias be present, in a way that only ated with better work outcomes in 1157 workers from the motivated workers with MS, with mild disease sever- the general population . The current study corrobo- ity were willing to participate in this research. Further- rates these findings in workers with MS as significant re- more, the questionnaires and especially the question on lations were found between a larger capability set and absenteeism may be influenced by a possible recall bias better work outcomes. Moreover, in workers with MS a [39, 40]. With the use of questionnaires we should also larger capability set was associated with better health in be aware of the possible response shift bias in both terms of self-reported cognitive and neuropsychiatric groups, in which cognitive biases shift the response of functioning, depression, anxiety and fatigue. Apparently, participants away from an accurate or truthful response a larger capability set for work is involved with a more . Furthermore, given the cross-sectional nature of productive and healthier life in workers with MS. Inter- this study, causal relationships between health and work estingly, the overall capability item ‘altogether, I think I outcomes cannot be established. have sufficient opportunities to continue to work’ was also associated with work functioning and cognitive and psychological health in workers with MS, and is add- Further research itionally correlated with measures of physical work func- The current study included a group of workers with tioning and work hours. This item seems to represent a MS characterized by mild disability and few cognitive very broad measure of work functioning and health. problems. Further research could benefit from includ- ing a more wide-spread MS phenotype to more thor- Strength and limitations oughly assess the spectrum of the Capability Set for To our knowledge, this is the first study to investigate Work in workers with MS. Moreover, to further ex- the ‘value of work’ in workers with MS. The question- plore sustainable employability over time in workers naire used to do so, is validated in one study using with MS, a longitudinal study is needed to evaluate workers from the general population . The CSWQ is the predictive validity of the questionnaire. It is of a fairly new instrument and we should keep in mind that interest to determine what level of discrepancy (A-B) it is important to further investigate its construct valid- poses a risk for future job loss. On an individual ity. In addition, the CSWQ is not specifically validated basis, it maythenbeusefultoidentify ‘risky’ discrep- for people with a chronic illness such as MS. Although ancies in importance and opportunity of each value, we do not have any reason to suggest that the construct so that workplace opportunities can be adjusted to of work capabilities is different in people with a chronic help workers with MS stay at work. van Gorp et al. Health and Quality of Life Outcomes (2018) 16:113 Page 10 of 11 Conclusion Competing interests DvG received honoraria for presentations from Sanofi Genzyme, outside the In conclusion we found that workers with MS rate work submitted work. PJ received honoraria from Bayer, Merck Serono and Teva values as more important and have a larger capability set Phamarceuticals for contributions to symposia as a speaker or for than workers from the general population. A larger cap- educational or consultancy activities, outside the submitted work. EA reports personal fees from honoraria for lectures, and honoraria for advisory boards ability set was related with better work outcomes in all from Teva Phamarceuticals, Merck Serono, Sanofi Genzyme, Biogen and workers and better health outcomes in workers with Novartis, outside the submitted work. JvE received honoraria for lectures, MS. Surprisingly, workers with MS felt they were given travel grants and honoraria for advisory boards from Teva Phamarceuticals, Merck Serono, Sanofi Genzyme, Biogen, Roche and Novartis, outside the more opportunities and were actually able to achieve submitted work. SF received honoraria for lectures, grants for research, and work values better, compared to the general population. advisory boards from Teva Phamarceuticals, Merck Serono, Sanofi Genzyme, The fact that the workplace offers less opportunities to Biogen, Novartis, and Roche, outside the submitted work. GH reports grants and personal fees from Biogen, Novartis, Teva Pharmaceuticals, Merck achieve valued work aspects relative to the importance Serono, and Sanofi Genzyme, outside the submitted work. RH received that is given to these aspects, raises concern. honoraria for lectures, grants for research and honoraria for advisory boards Given the health and productivity benefits of an in- from Merck Serono, Novartis, Sanofi Genzyme, Sanofi and Biogen, outside the submitted work. JM reports personal fees from Novartis, Merck Serono, creased set of work capabilities, such conflict needs to Sanofi Genzyme, Teva Phamarceuticals, outside the submitted work. WV be resolved for individual workers. This process may received honoraria for lectures from Biogen and Merck Serono, begin by identifying value conflicts and helping workers reimbursement for hospitality from Biogen, Teva Phamarceuticals, Sanofi Genzyme and Merck Serono, and honoraria for advisory boards from Merck and employers to create an optimal task description and Serono, outside the submitted work. DZ received honoraria for advisory a working environment in which important values can boards from Novartis, Merck Serono, Sanofi Genzyme and Biogen outside be achieved. The CSWQ might be a useful screening the submitted work. LV received honoraria for lectures, grants for research and honoraria for advisory boards from Sanofi Genzyme, Merck Serono, tool in this respect. Novartis and Teva Phamarceuticals. KvdH received honoraria for consultancies, presentations and advisory boards from Genzyme and Merck Abbreviations Serono, outside the submitted work. The other authors (JvdK, FA, IvL, EB, HB, CSWQ: Capability set for work questionnaire; EDSS: Expanded disability status JF, KdG, PP, MH, MR, HM) declare that they have no competing interests. scale; HADS: Hospital anxiety and depression scale; MFIS: Modified fatigue impact scale; MS: Multiple sclerosis; MSNQ: Multiple sclerosis neuropsychological screening questionnaire; RRMS: Relapsing-remitting multiple sclerosis; SDMT: Symbol digit modalities test; WAI: Work ability Publisher’sNote index; WRFQ 2.0: Work role functioning questionnaire 2.0 Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Acknowledgements Author details We thank the neurologist, MS (research) nurses, psychologists and other National Multiple Sclerosis Foundation, Mathenesserlaan 378, Rotterdam healthcare professionals involved with data acquisition. 3023 HB, The Netherlands. Department of Psychology, Section Health, Medical and Neuropsychology, Leiden University, PO Box 9555, Leiden 2300 Funding RB, The Netherlands. Department of Neurology, Elisabeth-TweeSteden This work was supported ZonMw (TOP Grant, project number: 842003003), Hospital, PO Box 90151, Tilburg 5000 LC, The Netherlands. Department of the Dutch National Multiple Sclerosis Foundation and Teva Pharmaceuticals. Care Ethics, University of Humanistic Studies, PO Box 797, Utrecht 3500 AT, The Netherlands. Tilburg School of Social and Behavioural Sciences, Tranzo Scientific Centre for Care and Welfare, Tilburg University, PO Box 90153, Availability of data and materials Tilburg 5000 LE, The Netherlands. Department of Community & The datasets used and/or analysed during the current study are available Occupational Medicine, University of Groningen, University Medical Centre from the corresponding author on reasonable request. Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands. MS4 Research Institute, Ubbergseweg 34, Nijmegen 9522 KJ, The Netherlands. Authors’ contributions van Lieshout Arbo Advies, PO Box 325, Uden 5400 AH, The Netherlands. DvG: study conception and design, data acquisition and analysis, study Department of Neurology, Medical Centre Leeuwarden, PO Box 888, coordination, wrote manuscript. JvdK, FA, MR, IvL and HM study conception and Leeuwarden8901 BRThe Netherlands. Department of Neurology, St. Anna design. PJ and MH data acquisition. KvdH: study conception and design, data Hospital, PO Box 90, Geldrop 5660 AB, The Netherlands. Department of acquisition, study coordination, wrote manuscript. LV: study conception and Neurology, Jeroen Bosch Hospital, PO Box 90153, s-Hertogenbosch 2000 ME, design, data acquisition, study coordination. The other co-authors in the The Netherlands. Department of Neurology, Amphia Hospital, PO Box MS@Work study group (EA, EB, HB, JvE, JF, SF, KdG, GH, RH, JM, PP, WV, and DZ) 90158, Breda 4800 RK, The Netherlands. Department of Neurology, St. were involved with the acquisition of data and local study coordination. All Antonius Hospital, PO Box 2500, Nieuwegein 3430 EM, The Netherlands. authors read, commented on the manuscript and approved the final manuscript. Department of Neurology, Groene Hart Hospital, PO Box 1098, Gouda 2800 BB, The Netherlands. Department of Neurology, Catharina Hospital, PO Box Ethics approval and consent to participate 1350, Eindhoven 5602 ZA, The Netherlands. Department of Neurology, The MS@Work study was approved by the Medical Ethical Committee Zuyderland Medical Centre, PO Box 5500, Sittard 6130 MB, The Netherlands. Brabant (NL43098.008.12 1307) and the Board of Directors of the Department of Neurology, Rijnstate Hospital, PO Box 9555, Arnhem 6800 participating MS outpatient clinics. All subjects provided written informed TA, The Netherlands. Department of Neurology, VieCuri Medical Centre, PO consent. For the panel study no ethical approval was necessary according to Box 1926, Venlo 5900 BX, The Netherlands. Department of Neurology, the medical ethics committee of the University Medical Centre Groningen as Canisius-Wilhelmina Hospital, PO Box 9015, Nijmegen 6500 GS, The it did not qualify for being tested according to the Dutch Medical Research Netherlands. Department of Neurology, Albert Schweitzer Hospital, PO Box Involving Human Subjects act of 1998 . 444, Dordrecht 3300 AK, the Netherlands. Department of Rehabilitation The panel study was performed according to the guidelines of the Medicine, University Medical Centre Groningen, University of Groningen, PO Association of Universities in the Netherlands . Participants provided Box 30.002, Haren 9750 RA, the Netherlands. Department of Neurology, online informed consent . Both studies were performed in agreement Leiden University Medical Centre, PO Box 9600, Leiden 2300 RC, The with the Declaration of Helsinki . Netherlands. van Gorp et al. Health and Quality of Life Outcomes (2018) 16:113 Page 11 of 11 Received: 31 January 2018 Accepted: 22 May 2018 23. Reilly MC, Zbrozek AS, Dukes EM. The validity and reproducibility of a work productivity and activity impairment instrument. PharmacoEconomics. 1993; 4:353–65. 24. Kurtzke JFMD. Rating neurologic impairment in multiple sclerosis: an expanded disability status scale (EDSS). Neurology. 1983;33:1444–52. References 25. Benedict RH, Cox D, Thompson LL, Foley F, Weinstock-Guttman B, 1. Ilmarinen JE. Aging workers. J Occup Environ Med. 2001;58:546–52. Munschauer F. Reliable screening for neuropsychological impairment in 2. Kroon AC, Vliegenthart R, Selm M. Between accommodating and activating: multiple sclerosis. Multp Scler J. 2004;10:675–8. framing policy reforms in response to workforce aging across Europe. Int J 26. Smith A. Symbol digit modalities test: Manual. Los Angeles: Western Press Polit. 2017;22:333–56. Psychological Services; 1982. 3. Abma FI, Brouwer S, de Vries HJ, Arends I, Robroek SJW, Cuijpers MPJ, van 27. Benedict RH, DeLuca J, Phillips G, LaRocca N, Hudson LD, Rudick R, der Wilt GJ, Bultmann U, van der Klink JJL. The capability set for work: Consortium MSOA. Validity of the symbol digit modalities test as a development and validation of a new questionnaire. Scand J Work Environ cognition performance outcome measure for multiple sclerosis. Multp Scler Health. 2016;42:34–42. J. 2017;23:721–33. 4. Saunders SL, Nedelec B. What work means to people with work disability: a 28. Zigmond AS, Snaith RP. The hospital anxiety and depression scale. Acta scoping review. J Occup Rehabil. 2014;24:100–10. Psychiatr Scand. 1983;67:361–70. 5. Compston A, Confavreux C, Lassmann H, McDonald I, Miller D, Noseworthy 29. Honarmand K, Feinstein A. Validation of the hospital anxiety and depression J, Smith K, Wekerle H: McAlphine's Multiple Sclerosis. In. Fourth edition. scale for use with multiple sclerosis patients. Mult Scler J. 2009;15:1518–24. London: Elsevier Inc; 2006. p. 298. 30. Kos D, Kerckhofs E, Nagels G, D'Hooghe BD, Duquet W, Duportail M, 6. Kobelt G, Berg J, Lindgren P, Anten B, Ekman M, Jongen PJ, Polman C, Ketelaer P. Assessing fatigue in multiple sclerosis: Dutch modified fatigue Uitdehaag B. Costs and quality of life in multiple sclerosis in the impact scale. Acta Neurol Belg. 2003;103:185–91. Netherlands. Eur J Health Econ. 2006;7(Suppl 2):S55–64. 31. Flachenecker P, Kumpfel T, Kallmann B, Gottschalk M, Grauer O, Rieckmann 7. Messmer Uccelli M, Specchia C, Battaglia MA, Miller DM. Factors that P, Trenkwalder C, Toyka KV. Fatigue in multiple sclerosis: a comparison of influence the employment status of people with multiple sclerosis: a multi- different rating scales and correlation to clinical parameters. Multp Scler J. national study. J Neurol. 2009;256:7. 2002;8:523–6. 8. Johnson KL, Yorkston KM, Klasner ER, Kuehn CM, Johnson E, Amtmann D. 32. J. Walker PA. Interpreting statistical findings: a guide for health professionals The cost and benefits of employment: a qualitative study of experiences of and students. Berkshire: Open University Press; 2010. persons with multiple sclerosis. Arc Phys Med Rehabil. 2004;85:201–9. 33. Paterson BL. The shifting perspectives model of chronic illness. J Nurs 9. Bartys S, Frederiksen P, Bendix T, Burton K. System influences on work Scholarsh. 2001;33:21–6. disability due to low back pain: an international evidence synthesis. Health 34. Shah D. Healthy worker effect phenomenon. Indian J Occup Environ Med. Policy. 2017;121:903–12. 2009;13:77–9. 10. van der Klink JJ, Bultmann U, Burdorf A, Schaufeli WB, Zijlstra FR, Abma FI, 35. Kirk-Brown A, Van Dijk P, Simmons R, Bourne M, Cooper B. Disclosure of Brouwer S, van der Wilt GJ. Sustainable employability-definition, diagnosis of multiple sclerosis in the workplace positively affects conceptualization, and implications: a perspective based on the capability employment status and job tenure. Multp Scler J. 2013; approach. Scand J Work Environ Health. 2016;42:71–9. 36. Bishop M, Frain MP, Tschopp MK. Self-management, perceived control, and 11. Sen AK. Equality of what? In: McMurrin S, editor. The Tanner lectures on subjective quality of life in multiple sclerosis. Rehabil Couns Bull. 2008;52:45–56. human values. Salt Lake City: University of Utah Press; 1980. p. 195–220. 37. Hooftman W, Houtman I. Netherlands: Employment opportunities for 12. Raggi A, Covelli V, Schiavolin S, Scaratti C, Leonardi M, Willems M. Work- people with chronic diseases. Den Haag: TNO; 2014. https://www. related problems in multiple sclerosis: a literature review on its associates eurofound.europa.eu/observatories/eurwork/comparative-information/ and determinants. Disabil Rehabil. 2016;38:936–44. national-contributions/netherlands/netherlands-employment-opportunities- 13. van der Hiele K, van Gorp DA, Heerings MA, van Lieshout I, Jongen PJ, for-people-with-chronic-diseases. Accessed 14 Dec 2017. Reneman MF, van der Klink JJ, Vosman F, Middelkoop HA, Visser LH, Group 38. Hooftman W, Mars G, Janssen B, de Vroome E, Janssen B, Michiels J, van MSWS. The MS@Work study: a 3-year prospective observational study on den Bossche S. Nationale Enquête Arbeidsomstandigheden 2015, factors involved with work participation in patients with relapsing-remitting Methodologie en globale resultaten. Leiden: TNO, Heerlen: CBS; 2015. multiple sclerosis. BMC Neurol. 2015;15:134. https://www.cbs.nl/nl-nl/publicatie/2016/20/nationale-enquete- 14. Polman CH, Reingold SC, Banwell B, Clanet M, Cohen JA, Filippi M, Fujihara K, arbeidsomstandigheden-2015. Accessed 14 Dec 2017. Havrdova E, Hutchinson M, Kappos L, et al. Diagnostic criteria for multiple 39. Coughlin SS. Recall bias in epidemiologic studies. J Clin Epidemiol. 1990;43:87–91. sclerosis: 2010 revisions to the McDonald criteria. Ann Neurol. 2011;69:292–302. 40. Beemster TT, van Velzen JM, van Bennekom CAM, Reneman MF, Frings- 15. Ministerie van Volksgezondheid, Welzijn en Sport: Dutch Medical Research Dresen MHW. Test–retest reliability, agreement and responsiveness of Involving Human Subjects Act. 1998. http://wetten.overheid.nl/ productivity loss (iPCQ-VR) and healthcare utilization (TiCP-VR) BWBR0009408/2017-03-01. Accesed 14 Dec 2017. questionnaires for sick workers with chronic musculoskeletal pain. J Occup 16. VSNU Gedragscode voor gebruik van persoonsgegevens in Rehabil. 2018;1–13. https://doi.org/10.1007/s10926-018-9767-9. wetenschappelijk onderzoek. http://vsnu.nl/files/documenten/Domeinen/ 41. Howard JS, Mattacola CG, Howell DM, Lattermann C. Response shift theory: Onderzoek/Code_wetenschapsbeoefening_2004_%282014%29.pdf. Accesed an application for health-related quality of life in rehabilitation research and 14 Dec 2017. practice. J Allied Health. 2011;40:31–8. 17. World Medical Association. World Medical Association Declaration of Helsinki: ethical principles for medical research involving human subjects. Jama. 2013;310:2191–4. 18. Verhage F. Intelligentie en leeftijd bij volwassenen en bejaarden. Groningen: Koninklijke Van Gorcum; 1964. p. 98. 19. Tuomi KIJ, Jahkola A, Katajarinne L, Tulkki A. Work Ability Index: Helsinki: Finnish Institute of Occupational Health; 1998. 20. Ahlstrom L, Grimby-Ekman A, Hagberg M, Dellve L. The work ability index and single-item question: associations with sick leave, symptoms, and health-a prospective study of women on long-term sick leave. Scand J Work Environ Health. 2010;36:404–12. 21. Abma FI, van der Klink JJ, Bultmann U. The work role functioning questionnaire 2.0 (Dutch version): examination of its reliability, validity and responsiveness in the general working population. J Occup Rehabil. 2013;23:135–47. 22. Ware J Jr, Kosinski M, Keller SD. A 12-item short-form health survey: construction of scales and preliminary tests of reliability and validity. Med Care. 1996;34:220–33.
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