Leading article

Aortic aneurysm screening A. M. van Rij and G. T. Jones Department of Surgical Sciences, Dunedin School of Medicine, University of Otago, PO Box 56, Dunedin 9054, New Zealand (e-mail: [email protected])

Published online in Wiley Online Library (www.bjs.co.uk). DOI: 10.1002/bjs.9830

Fig. 1

Ultrasound screening for abdominal aortic aneurysm

Screening for abdominal aortic aneurysm (AAA) saves lives. It can be carried out successfully in large communities and across the population of whole countries. It is a cost-effective strategy when applied to men aged 65 years who are, or have been, smokers, even with the falling prevalence of AAA at age 65 years in men from 4 per cent down to 1⋅1 per cent. Wider implementation would seem inevitable, based on excellent models in the UK and Sweden1,2 (Fig. 1). There is still reluctance, however, to do this on a national scale in other parts of the world, despite general support from vascular surgeons and others treating this condition. This hesitation is not only related © 2015 BJS Society Ltd Published by John Wiley & Sons Ltd

to the magnitude of the effort required to implement such largescale programmes but also due to some of the uncertainties around the model of screening, the natural history of AAA, variations in access and the appropriateness within different systems of health service delivery. Some of these factors affecting the feasibility and efficacy of screening are raised in a group of papers on AAA screening in this issue of BJS. They point to the requirement for future refinements, and continuing changes. Not only is there the changing prevalence of AAA, which may be attributable to the decline in smoking and likely to be influenced by better management of other cardiovascular

disease risk factors, but there is also improvement in treatment outcomes, with greater numbers of endoluminal repairs, and reduced early procedural mortality and morbidity, as well as changing expectations for intervention. These sociological and technological changes will continue to modify what determines efficient and effective screening. The limitations of the most widely preferred model of a ‘once in a lifetime’ screening aortic scan in 65-year-old men have become apparent. The realization that aortas just below 3 cm in diameter do continue to enlarge after the age of 65 years, and become clinically relevant in later years, is critical for screening in BJS 2015; 102: 863–865

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populations with increasing longevity. Ruptured AAA is more common in those aged more than 75 years and the expectation for intervention in older age groups has increased. This raises the need for repeat scanning in older populations3 . Equity of access is an important consideration in making the case for screening, and the current approaches often struggle to achieve this. Although AAA is considered a male-dominated disease for screening, 20–30 per cent of AAAs occur in women. These occur at a slightly older age and have worse outcomes from both rupture and elective intervention. The threshold aortic size for AAA intervention in women should be smaller than current convention, and this sex difference must be addressed. Similarly, those under 65 years of age (10–15 per cent of AAAs) are excluded, for whom rupture prevention would save each individual more life-years. Non-smokers do get AAA (20 per cent overall, and more so in women) and they similarly may be excluded. Access is not limited just by the screening criteria, but also by the ability and willingness of individuals to attend. It has been thought that those living more remotely or rurally would respond less frequently to screening, but this has been disproven4 , suggesting that response rates in smaller districts are as good if not better than those in large urban communities. Those from lower socioeconomic settings do, however, respond less frequently5 . Measures to improve response rates are always a challenge to screening programmes. Inviting people to be screened at smaller local units appears to improve attendance compared with attending more centralized locations4 . Risk stratification of the population to be screened is a means to optimize the detection rate of AAA. It is used in © 2015 BJS Society Ltd Published by John Wiley & Sons Ltd

A. M. van Rij and G. T. Jones

current large-scale models (men, aged 65 years and smokers at any time), but other risk criteria can be used successfully. These include groups previously excluded from screening. The prevalence of AAA is increased in those with coronary artery disease, peripheral vascular disease and hypertension. This suggests that other risk stratification models could be used to identify alternative populations with higher prevalence for more focused AAA screening. Other factors also influence prevalence, which may affect national approaches to screening. For example, in New Zealand the indigenous M¯aori people, especially women, have a higher prevalence of AAA than expected, with the added significance that aneurysms occur and rupture at a younger age6 . These require additional local strategies to provide equitable screening. The assumption that a dedicated stand-alone population screening programme for AAA is required should be revisited. Other screening opportunities are available, or under consideration, for populations with overlapping increased AAA risk. These include screening for atrial fibrillation, cardiovascular risk, and colorectal, lung, prostate and breast cancer. Coordination of screening opportunities may improve participation and reduce costs7,8 . Much of this already occurs through community health practices assisted by sophisticated technological linkages and financial incentives to promote screening participation. In addition, patients attending cardiology services and vascular assessment laboratories have a higher prevalence of AAA and could be offered screening at the same point of contact9 . A large proportion of clinical AAAs are increasingly detected incidentally or opportunistically. The increasing use of abdominal ultrasonography, www.bjs.co.uk

CT, colonography and MRI must affect screening practices. Not only do they detect obvious AAAs, but they could also confirm normal aortas for which screening is not required. Whether small AAAs are picked up as consistently is not known. A heightened awareness of the aortic size criteria for small aneurysms in current imaging practices may contribute to a screening strategy with little added cost. What about the future? The practical application of genomics to screening may not be far off for AAA. A number of genetic markers are known and are likely to contribute to risk prediction10 . The cost and availability of genetic testing have improved and, in time, AAA genetic risk will become part of an affordable standard screening package. Medical therapy for prevention of AAA expansion will certainly change the screening landscape. Most studies exploring medical management have not yet shown benefit11 , but there seems an inevitability that this will happen, with refinements in personalized pharmacogenetics. Whether the many options available to improve outcomes for those at risk of ruptured AAA are implemented or not depends on governments and health authorities with very different philosophies, systems, priorities and resources. They may also ask ‘Is it really worth it?’ when screening leads to overdiagnosis, doubles preventive surgery, and adds anxiety and costs of surveillance to the many people with small aneurysms who will never require treatment12 . The papers in this month’s BJS provide valuable observations from established screening programmes that will inform these considerations. Disclosure

The authors declare no conflict of interest. BJS 2015; 102: 863–865

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References 1 Davis M, Harris M, Earnshaw JJ. Implementation of the National Health Service Abdominal Aortic Aneurysm Screening Program in England. J Vasc Surg 2013; 57: 1440–1445. 2 Wanhainen A, Björk M. The Swedish experience of screening for abdominal aortic aneurysm. J Vasc Surg 2011; 53: 1164–1165. 3 Howard DPJ, Banerjee A, Fairhead JF, Handa A, Silver LE, Rothwell PM. Age-specific incidence, risk factors and outcome of acute abdominal aortic aneurysms in a defined population. Br J Surg 2015; 102: 907–915. 4 Crilly MA, Mundie A, Bachoo P, Nimmo F. Influence of rurality, deprivation and distance from clinic on uptake in men invited for abdominal aortic aneurysm screening. Br J Surg 2015; 102: 916–923. 5 Zarrouk M, Holst J, Malina M, Lindblad B, Wann-Hansson C, Rosvall M et al. The importance of

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socioeconomic factors for compliance and outcome at screening for abdominal aortic aneurysm in 65-year-old men. J Vasc Surg 2013; 58: 50–55. Nair N, Shaw C, Sarfati D, Stanley J. Abdominal aortic aneurysm disease in New Zealand: epidemiology and burden between 2002 and 2006. N Z Med J 2012; 125: 10–20. Grøndal N, Søgaard R, Lindholt JS. Baseline prevalence of abdominal aortic aneurysm, peripheral arterial disease and hypertension in men aged 65–74 years from a population screening study (VIVA trial). Br J Surg 2015; 102: 902–906. Bath MF, Gokani VJ, Sidloff DA, Jones LR, Choke E, Sayers RD et al. Systematic review of cardiovascular disease and cardiovascular death in patients with a small abdominal aortic aneurysm. Br J Surg 2015; 102: 866–872. Aboyans V, Kownator S, Lafitte M, Brochet E, Emmerich J, Tribouilloy C

et al. Screening abdominal aorta aneurysm during echocardiography: literature review and proposal for a French nationwide study. Arch Cardiovasc Dis 2010; 103: 552–558. 10 Jones GT, Bown MJ, Gretarsdottir S, Romaine SP, Helgadottir A, Yu G et al. A sequence variant associated with sortilin-1 (SORT1) on 1p13.3 is independently associated with abdominal aortic aneurysm. Hum Mol Genet 2013; 22: 2941–2947. 11 Sillesen H, Eldrup N, Hultgren R, Lindeman J, Bredahl K, Thompson M et al. Randomized clinical trial of mast cell inhibition in patients with a medium-sized abdominal aortic aneurysm. Br J Surg 2015; 102: 894–901. 12 Johansson M, Hansson A, Brodersen J. Estimating overdiagnosis in screening for abdominal aortic aneurysm: could a change in smoking habits and lowered aortic diameter tip the balance of screening towards harm? BMJ 2015; 350: h825.

Editor’s comments

In defence of national screening programmes for AAA, anything less is a compromise. National programmes are complicated and tricky to organise, and they are costly to implement. Yet, managing patients with ruptured AAA is expensive, and even at contemporary prevalence, screening 65-year-old men remains very cost-effective. The hallmarks of national programmes are equity of invitation and monitoring of quality standards, both for imaging and intervention. The National Health Service (NHS) AAA Screening Programme in England has recently undergone a review, following which the UK National Screening Committee will be consulted over extending surveillance intervals for small AAA, and possible repeat invitation for men with aortic diameter just below 3 cm at age 65. The issue of screening women for AAA remains controversial; while AAA prevalence in women is even lower than in men, about one-third of deaths from AAA are now in women. The National Institute for Health Research (NIHR) Health Technology Assessment (HTA) Programme has recently funded a modelling project to assess whether screening women would also be worthwhile. Additionally, the project will also investigate whether screening should be implemented differently for women compared with the current programme for men. Anyone with relevant unpublished data on AAA in women (for example on prevalence, surgical mortality, turn-down rates, long-term follow-up after surgery) is invited to contact the principal investigator, Professor Simon Thompson at the University of Cambridge: [email protected]. J. J. Earnshaw Joint Chief Editor, BJS

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BJS 2015; 102: 863–865

Aortic aneurysm screening.

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