TY - JOUR
AU - Earnshaw, J J
AB - Abstract Background The Abdominal Aortic Aneurysm (AAA) Screening Programme was introduced by the National Health Service (NHS) in England to reduce the rate of death from ruptured AAA in men. The programme commenced in 2009 and was implemented completely across the country in April 2013. The aim was to review the first 5 years of the programme, looking specifically at compliance and early outcome. Methods Men aged 65 years were invited for a single abdominal ultrasound scan. Data were entered into a bespoke database (AAA SMaRT). This was a planned analysis after the first 5 years of the programme. Results The summation analysis involved the first 700 000 men screened, and the first 1000 men with a large AAA referred for possible treatment. The prevalence of AAA (aortic diameter larger than 2·9 cm) in 65-year-old men was 1·34 per cent. Mean uptake was 78·1 per cent, but varied from 61·7 to 85·8 per cent across the country. Based on the Index of Multiple Deprivation, uptake was 65·1 per cent in the most deprived versus 84·1 per cent in the least deprived areas. Of the first 1000 men referred for possible treatment of a large AAA (greater than 5·4 cm), the false-positive rate was 3·2 per cent. Some 870 men underwent a planned AAA intervention (non-intervention rate 9·2 per cent), with seven deaths (perioperative mortality rate 0·8 per cent). Conclusion The processes in the NHS AAA Screening Programme are effective in detecting and treating men with AAA. Introduction The National Health Service (NHS) Abdominal Aortic Aneurysm (AAA) Screening Programme (NAAASP) was introduced in England to reduce the risk of death from ruptured AAA in men1. Approximately 3000–4000 people die from the condition annually in England and Wales, concentrated mainly in men over 65 years of age2. Screening for AAA in England followed approval by the UK National Screening Committee in 2007, which considered international evidence, including the results of the UK Multicentre Aneurysm Screening Study3. Population screening of men aged 65 years commenced in 2009, and was implemented across the whole of England in April 2013. Full details of the programme have been published4. Similar programmes have started in Wales, Scotland and Northern Ireland. The present study reviewed the results of the first 5 years among 65-year-old men who attended for ultrasound screening, and the first cohort of men referred for treatment of a large aneurysm (over 5·4 cm). The aim was to check the systems and processes in the programme. Methods Details of the standard operating procedure are available at: https://www.gov.uk/government/collections/aaa-screening-supporting-documents. Briefly, men aged 65 years were invited by standard letter to attend a local community setting for a portable abdominal ultrasound scan. Men known to have an AAA were excluded from screening. After imaging, those with an abdominal aorta less than 3·0 cm in diameter were reassured and discharged; men with an aortic diameter of 3·0–5·4 cm were offered regular ultrasound surveillance; and men whose initial aortic diameter was greater than 5·4 cm, or whose aneurysms grew to that diameter during surveillance, were referred to a vascular service for possible intervention. Men in surveillance received advice from a vascular nurse specialist concerning healthy lifestyle, smoking cessation and diet, and were recommended to take antiplatelet and statin therapy, unless contraindicated. Men over the age of 65 years were not invited, but could self-refer to their local programme for a screening scan, with the findings managed as for invited men. Screening was coordinated from 41 local programmes, each based around minimum populations of approximately 800 000. Each local programme was linked to one or more accredited vascular centres. Ultrasound imaging was done by dedicated screeners trained to image the infrarenal aorta in a standard fashion who were subject to regular quality assurance. The anteroposterior diameter of the infrarenal aorta was measured using the inner wall to inner wall method5, from a static image of the widest part, which was stored for quality assurance. The results of screening were entered into the database. The man was informed of the result immediately and a letter with this information sent to the family practitioner. Data on invitation and screening were collected in a bespoke database (AAA SMaRT). Each year the cohort of men aged 65 years was downloaded into AAA SMaRT, from where a call and recall system was used to invite men and record the outcomes of the screening episode. When a man attended for screening, he completed a consent process agreeing that his data could be stored and used for analysis and research. The present report is a planned analysis after the first 5 years of the programme based on aggregated data from AAA SMaRT, and looking at compliance and early outcome. Surgical outcome data, including 30-day postoperative mortality rates, were corroborated with results recorded in the National Vascular Registry, the database of procedures recorded by members of the Vascular Society of Great Britain and Ireland. The present report is a summation analysis of the first 700 000 men who had their first scan following invitation, and the first 1000 men with an AAA over 5·4 cm in diameter referred for treatment. The first 1000 men referred were collected before 700 000 men had been screened, but this number was selected as a suitable sample for analysis, with at least 6 months of follow-up for outcome research (all men should have undergone surgery with at least 30 days of follow-up). Uptake was compared across geographical areas and across varying social deprivation, measured using the Index of Multiple Deprivation (IMD) scores, 20106. Changes in prevalence over time were assessed using χ2 for trend. Results First 700 000 men screened The first men were invited in 2009 by the early adopter programmes. Other programmes were implemented over the next 4 years, completing in 20134. The April 2013 to April 2014 cohort was the first complete national cohort offered an invitation to attend for screening. Each annual cohort consisted of approximately 300 000 men. Incomplete cohorts were scanned during implementation. A total of 896 287 men were invited for screening and 700 000 attended (uptake rate 78·1 per cent). The mean aortic diameter was 1·8 cm, ranging from 0·7 to 11·1 cm (Fig. 1a,b). A total of 690 612 men (98·7 per cent) had an aorta less than 3·0 cm in diameter. They were reassured and discharged from the programme. There was an incidence spike at 3·0 cm. Some 7605 men (1·09 per cent) had a small AAA (3·0–4·4 cm in diameter) and 1028 (0·15 per cent) had a medium-sized AAA (4·5–5·4 cm). They were entered into a surveillance programme with recall for ultrasound imaging after 1 year or 3 months respectively. A total of 755 men (0·11 per cent) had a large AAA exceeding 5·4 cm at initial scan. These men were referred to their local vascular service for consideration of treatment. The overall prevalence of AAA (aortic diameter over 2·9 cm) at first scan in this cohort was 1·34 per cent, with evidence that the prevalence was falling annually (Pearson correlation coefficient 174·18, P < 0·001) (Fig. 2). Fig. 1 Open in new tabDownload slide Maximum aortic diameter measurements for the first 700 000 men screened in the National Health Service Abdominal Aortic Aneurysm (AAA) Screening Programme in England: a 0·7–5·4 cm and b greater than 5·4 cm Fig. 2 Open in new tabDownload slide Rate of aneurysms detected (aortic diameter over 2·9 cm) per 1000 men screened and number of men screened by screening year. Error bars show 95 per cent confidence intervals. There was a gradual reduction in prevalence over time (Pearson correlation coefficient 174·18; P < 0·001, χ2 test for trend). The result was similar when data for 2009–2010 were excluded The rate of acceptance of a screening offer varied across the country, ranging from 61·7 per cent in North West London to 85·8 per cent in South Devon (Figs 3 and 4). Uptake was affected by social deprivation6. The acceptance rate was 65·1 per cent in the most deprived, and 84·1 per cent in the least deprived areas of England (Fig. 5). Fig. 3 Open in new tabDownload slide Percentage uptake by local screening programme of men scanned following an invitation for screening. Error bars show 95 per cent confidence intervals Fig. 4 Open in new tabDownload slide Percentage uptake of men scanned following an invitation for screening by local lower-tier authority area (first 896 287 scans). Insert shows Greater London. Contains Ordnance Survey data © Crown copyright and database right 2016. Contains National Statistics data © Crown copyright and database right 2016. Fig. 5 Open in new tabDownload slide Percentage uptake of initial screening by decile of deprivation, according to Index of Multiple Deprivation (IMD) 2010 scores adjusted to 2011 Lower Super Output Areas. Median values (bold line) are shown with i.q.r. (box) and range (error bars) During the same interval, a total of 29 999 men aged over 65 years self-referred, with 27 421 being tested. Of these, 26 654 (97·2 per cent) had an aortic diameter below 3·0 cm; 633 (2·31 per cent) had a small AAA and 92 (0·34 per cent) a medium AAA, and were placed in surveillance, using the same intervals as above. Some 42 men had an AAA larger than 5·4 cm (0·15 per cent). First 1000 men referred for treatment The first 1000 men with a large AAA were originally referred to their local NAAASP-accredited vascular centre between April 2009 and July 2013. Of these, 508 were 65-year-old men with a large AAA detected at first screening scan, 430 (median age 67 years) were men who had a small or medium AAA that expanded to over 5·4 cm during routine ultrasound surveillance, and the remaining 62 had referred themselves, and were found to have a large AAA at initial (42) or subsequent (20) surveillance scan. Some 990 men were seen in a vascular service, whereas ten declined. A large AAA was confirmed in 958 men. In 11 a false-positive result was diagnosed after CT angiography (aortic diameter below 5·5 cm), and other non-specified diagnoses were uncovered in 21, including an enlarged bladder and mesenteric cyst. The overall false-positive rate was 3·2 per cent. After investigation and discussion, 870 men subsequently had AAA repair, a median of 10 (range 0–202, mean 16) weeks after referral (initial non-intervention rate 9·2 per cent). Some 352 men (40·5 per cent) were treated within the national standard of 8 weeks after referral. Initial non-intervention was more common in men who came from surveillance or self-referral: odds ratio 2·26 (95 per cent c.i. 1·56 to 3·29). Of the remaining 88 men, 57 were considered unfit or unsuitable for intervention, or declined. They were discharged from the vascular service. A further 31 men (mean age 72 (range 64–86) years) were considered unsuitable for AAA treatment after investigation at that time and were placed back on surveillance, the implication being that the decision might be altered if the AAA continued to enlarge. Two men had private treatment outside the NHS and one man had surgery planned. Six men died after referral but before treatment was undertaken, two while under assessment; two deaths were not AAA-related and two men died from a ruptured AAA, one of whom chose not to have treatment and the other delayed having treatment. Of 870 men who had a planned intervention, 448 had conventional open AAA repair, 402 underwent endovascular AAA repair (EVAR), and the type of procedure was unknown in the remaining 20. There were seven postoperative deaths after elective AAA surgery. The perioperative mortality rate was 0·9 per cent after open AAA repair and 0·7 per cent after EVAR. Duration of hospital stay after open repair was longer than that after EVAR (median 7 versus 3 days). Discussion This first large-scale report from the NAAASP describes the 5 years from implementation up to, and including the first full cohort year of screened 65-year-old men. Almost one million men in England have now been invited for AAA screening. The NAAASP was designed to maximize the detection of AAA in men and then to refer for elective treatment before rupture. The general procedures used in NAAASP in England are similar to those employed by screening teams in the rest of the UK (Scotland, Northern Ireland and Wales), with the intention of producing UK-wide data on the results of AAA screening. The present results are similar to those seen in Sweden, the only other country using a national invitation and screening schedule7. The mean uptake rate, however, is greater in Sweden (85 versus 78·1 per cent in England), where attendees pay a small fee for having the scan. AAA screening is free in the UK. The uptake rate was variable across England and may have depended on a number of factors, including rurality and deprivation. Others have also found that deprivation and distance to travel to the screening centre affect uptake8. Ensuring equality of information and access to AAA screening among men in England may mean improving communication to enhance awareness, and expanding the use of the AAA decision support tool9. The prevalence rate of AAA (1·34 per cent) in the NAAASP was lower than that in screening trials (4·7 per cent in the Multicentre Aneurysm Screening Study3), probably reflecting the changing epidemiology of aortic and other vascular diseases, as smoking rates reduce and the use of statins increases10. The incidence of ruptured AAA is falling in many countries worldwide11,12. Countries with smoking rates that are not declining also find higher AAA prevalence on screening13. The Multicentre Aneurysm Screening Study included 65–74-year-old men, whereas only those aged 65 years were invited here. Swedish prevalence rates are higher (1·7 per cent) than in the present study, but men with a known AAA are not screened in England. In Sweden, sophisticated data matching demonstrated that approximately 0·5 per cent of 65-year-old men in that country were already known to have an AAA, or to have had a previous repair7. The prevalence spike at 3·0 cm suggests that screeners were reluctant to discharge men just below the threshold for surveillance. The NAAASP seems cost-effective and is projected to remain so, unless the prevalence of AAA in 65-year-old men falls below 0·35 per cent14. Screening is also considered cost-effective in Sweden at current epidemiology and intervention rates15. Outcomes of treatment are reassuring at present. The programme currently refers around 400 men for treatment of a large AAA every year. This will increase as the screened cohort enlarges. Analysis of the first 1000 men referred included both those under surveillance, who are naturally older, and 65-year-old men following their first scan. The mean wait for treatment after referral was too long at 16 weeks. The access target set by the NAAASP, that 80 per cent of procedures should be completed within 8 weeks of referral, was met for only 40·5 per cent of this cohort, although some of those not treated within 8 weeks may have needed treatment for co-morbidities, or may have chosen to delay the intervention. Perioperative elective mortality rates of less than 1 per cent compared favourably with the National Vascular Registry rate of 1·5 per cent in 201516, although this has been falling in the past 10 years17, owing to the contribution of the preimplementation quality processes, facilitated by the NAAASP, and the centralization of vascular surgery into larger networks18,19. Many vascular surgeons believe that men aged 65 years should be treated preferentially by open AAA repair, as long as they are fit enough, because there remains concern about the durability of EVAR in this younger group20. Mortality rates after surgery for screen-detected AAA in this series were lower than those for AAA detected incidentally21. The first cohort of 65-year-old men referred for surgery represents a valuable group, who could be followed to investigate late outcomes of open repair and EVAR in the younger man. The present analysis has limitations. There are no data on the 21·9 per cent of 65-year-old men who did not attend for screening. There is some evidence that this cohort has a slightly higher prevalence of AAA, as it includes some men for whom their health is not a priority. Outcomes in this group may be collected using national statistics in the future and will determine the true effectiveness of the programme. Similarly, the false-negative rate (AAA missed on screening) is unknown; this might also become evident through data linkage and national mortality statistics, although coding of cause of death is notoriously inaccurate. The NAAASP does not collect co-morbidity data for men who screened negative, so comparisons between populations with and without AAA were not possible. Now that the NAAASP is fully implemented, it enters the quality assurance phase and efforts will be made to ensure equality of access and information to all men in the UK, in particular to disadvantaged groups. Meanwhile, there are emerging data that could help to make the current programme more efficient and effective22. The standard operating procedure is based on a 20-year-old randomized trial, and is currently undergoing review to determine whether existing pathways can be improved. Potential adjustments to the current programme might involve altering surveillance scan intervals23 and rescreening men with an aortic diameter just below the 3·0-cm threshold24. The changing epidemiology of AAA may reduce the effectiveness of screening25, but current data suggest that it will remain cost-effective for the foreseeable future14. Acknowledgements The authors thank A. Scott and B. Heather whose pioneering work is the bedrock for the NAAASP. Implementation also relied on the support and enthusiasm of the 41 local screening programmes and their staff, and the present results are a tribute to them. The authors also acknowledge valuable advice from R. Sherriff and A. Mackie. The NAAASP is funded by the Department of Health and provided through Public Health England. Disclosure: The authors declare no conflict of interest. References 1 NHS Screening Programmes . Essential Elements in Providing an Abdominal Aortic Aneurysm (AAA) Screening and Surveillance Programme . https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/491872/2015-11-02_SOPs_v4.02.pdf [accessed 10 March 2016]. 2 Anjum A , von Allmen R, Greenhalgh R, Powell JT. Explaining the decrease in mortality from abdominal aortic aneurysm rupture . Br J Surg 2012 ; 99 : 637 – 645 . 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Google Scholar Crossref Search ADS PubMed WorldCat © 2016 BJS Society Ltd Published by John Wiley & Sons Ltd This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) © 2016 BJS Society Ltd Published by John Wiley & Sons Ltd
TI - Impact of the first 5 years of a national abdominal aortic aneurysm screening programme
JF - British Journal of Surgery
DO - 10.1002/bjs.10173
DA - 2016-07-18
UR - https://www.deepdyve.com/lp/oxford-university-press/impact-of-the-first-5-years-of-a-national-abdominal-aortic-aneurysm-1qVOWyFwp8
SP - 1125
EP - 1131
VL - 103
IS - 9
DP - DeepDyve
ER -