EDUCATION & DEBATE

Reducing the mortality from abdominal aortic aneurysms: need for anational screening programme

P L Harris

The incidence of abdominal aortic aneurysms in theBritish Isles as in other Western countries has risendramatically during the second half of this century.'Not only has there been a steady expansion in thepopulation of elderly men, who are most at risk,2 butthere is also evidence of a true increase in age specificprevalence,' which may be related to progressivetransmission of a familial predisposition to the disease.4These trends seem set to continue.

Against this background it is a matter for seriousconcern that the interventions ofthe medical professionhave not had more impact on the very high mortalityassociated with this condition. Lack of an effectivetreatment is not the problem. -In the best centreselective surgical repair of abdominal aortic aneurysmscarries an operative risk of under 5% and a subsequentlongevity and quality of life which compares veryfavourably with normal expectations.5 The persistentlyhigh mortality is accounted for by the fact that asubstantial majority of aneurysms remain asymp-tomatic until the moment of rupture, when it is usuallytoo late for effective intervention. Of patients whoreach hospital alive, between 50% and 70% can besaved by emergency surgery, but we know that manymore die with a suddenness which denies them thebenefit of hospital treatment.6 Often the cause of deathis incorrectly diagnosed,6`8 and because precisestatistics are lacking the true death rate from rupturedaneurysms is unknown. An attempt to identify alldeaths from this cause within a defined communityduring a fixed period of time in Swansea indicated thata figure of between 80% and 90% is realistic,7 and thisaccords with the findings of a similar study fromStockholm.8

Vascular Surgical Societyof Great Britain and IrelandP L Harris, secretary

Correspondence to:Mr P L Harris, ConsultantVascular Surgeon,Broadgreen Hospital,Liverpool L14 3LB.

BMJ7 1992;305:697-9

Screening for aneurysmIn England and Wales, with a total population of

about 47 000 000, it is estimated that between 6000 and10 000 people die each year from rupture of anabdominal aortic aneurysm and that during the sameperiod around 3000 undergo successful elective oremergency surgical treatment.4 The key to bettersurvival is detection of the asymptomatic lesion leadingto a higher proportion of elective operations, andin practice this means population screening. Pilotstudies in Birmingham,9 Gloucester,'0 Oxford,"and Chichester'2 have shown convincingly that massscreening for aneurysms is not only feasible but iseffective and relatively inexpensive. Furthermore,their collective experience indicates that a nationwidescreening programme would be relatively easy toimplement and administer.The first requirement is the availability of a univers-

ally applicable method of diagnosis with a high degreeof patient acceptability. Portable ultrasound scannershave been shown to meet these needs. B modeultrasound imaging has long been recognised as the

optimum method for diagnosing abdominal aorticaneurysms.'3 An error of up to 10% associated withobjective mensuration of aortic diameters and anacknowledged difficulty in determining the preciserelation between the proximal limit of dilatation andthe ostia of the renal arteries do not detract from thereliability with which an aneurysm can be diagnosed bya skilled operator.'4 Portable machines, it seems, haveretained this essential diagnostic dependability whileminiaturisation has conferred other attributes notpossessed by their more cumbersome predecessors.9-'2The technique of examination is non-invasive, safe,free of discomfort for the patient, and readily repeat-able. The equipment can be operated by a radiographeror vascular nurse in a hospital clinic, general prac-titioner's surgery, or even the patient's own home, andthe cost per examination is extremely low."'

Population at risk and complianceSecondly, for mass screening to be realistic the

prevalence of the disease among those screened mustbe high, and it is therefore important to be able todefine a population at risk. Abdominal aortic aneurysmis predominantly a disease of men past middle age andis uncommon in women except for the very elderly. '5The greatest relative importance of the disease is inmen aged 70-74, in whom it accounts for 1-72% of alldeaths.'6 In Birmingham screening of 2669 asymp-tomatic men between the ages of 65 and 75 disclosed219 (8-2%) with an aortic diameter greater than 29mmand 70 (2-6%) with an aortic diameter in excess of40mm.9 Results from other studies in the UnitedKingdom have been broadly similar.' 1'2 Their collec-tive evidence suggests that a programme to screen allapparently healthy men once, on or about their 65thbirthday, will detect the majority of aneurysms. Otherespecially high risk groups are male siblings of patientswith aneurysms, a quarter of whom also have thedisease,'7 18 and patients who present other mani-festations of chronic arterial disease-for example,those with intermittent claudication, in whom theincidence is 10-15%.'9 They require special provisionfor screening irrespective of any plans to screenapparently healthy people.An important factor which can seriously undermine

the value of any screening programme is low patientcompliance. Experience from studies in the UnitedKingdom shows that response rates vary from about50% in inner city areas to over 85% in middle classsuburbs.9 A policy of involving local general prac-titioners and arranging examinations close to thepatients' homes appears to contribute significantly to ahigh rate of compliance,20 and there is therefore astrong case for any future national programme to beimplemented with the close involvement of localcommunity services and family practitioner commit-tees. Special efforts to overcome any inertia of in-

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Screening for abdominal aorticaneurysm with portableultrasound scanner

habitants ofinner cities are unlikely to yield worthwhilereturns. This is regrettable since it is probable thatthese communities include a higher proportion thanaverage of people at risk of arterial disease andtherefore abdominal aortic aneurysms. Though theeffectiveness of screening would undeniably be reducedby the reticence of this important minority, theindications are that a sufficiently large majority of thoseat risk would be prepared to participate to ensure thata nationwide programme would yield significantbenefits.9-2

TreatmentHaving detected previously unsuspected disease,

there must be the means available for effective treat-ment. A relative drawback as far as aortic aneurysmsare concerned is that major surgery is required. Thisimposes the need for selective application. Because therisk of rupture of an aneurysm increases exponentiallywith its size its diameter is the main determinant of theneed for treatment. Operation is justified for aneurysmsof 5 * 5 cm diameter or over. In these circumstances theonce only risk of definitive surgery compares veryfavourably with the risk of spontaneous rupture, whichis cumulative in the order of 7% a year.2' Operation isnot warranted initially for patients with aneurysmssmaller than 4-0 cm diameter, in whom the risk ofspontaneous rupture is very low and exceeded by therisk of death from associated ischaemic heart disease.22These patients require regular follow up at intervalswith repeated ultrasound scanning. Rather less certainis the most appropriate management policy foraneurysms with a diameter between 4 0 and 5 5 cm. Alarge multicentre randomised trial is under way in theUnited Kingdom which may resolve this problem (theUnited Kingdom small aneurysm trial).

For the future there is optimism that an effectiveendovascular alternative to conventional surgery maynot be too far away. A composite stent graft device hasalready been deployed with success in a small numberof carefully selected patients,23 and other prototypesare currently in various stages of development. Allemploy the same basic principles. A device which iseither self expanding or can be expanded over a ballooncatheter is introduced in compacted form on or withina transluminal catheter system via a remote site such asthe common femoral artery. It is then positionedwithin the aneurysm under radiological control andreleased to form a lining or inner tube which willprevent further expansion or rupture of the sac. Aspresently envisaged, it seems likely that this type oftechnique will be most readily applicable to smalluncomplicated aneurysms and, for reasons statedabove, an extremely low complication rate is anessential prerequisite to justify active intervention forsuch lesions. The potential for broadening the range ofpatients to whom definitive treatment might be offeredis, however, considerable. The successful evolution ofendovascular procedures is particularly pertinent toscreening programmes since two thirds of aneurysmsidentified by this means are under 4 cm diameter.9

For the present, conventional surgery represents aneffective means of treating those at greatest risk ofdeath from rupture of their aneurysm, and on the basisof the valuable information which is now availablefrom studies conducted in the United Kingdom usingthis method alone, the Vascular Surgical Societyis recommending that population screening forabdominal aortic aneurysms should be extendednationwide. It is believed that to do so would make animportant contribution to the government's ownrecently declared objective of "adding years to life"as enunciated in the white paper The Health of theNation. 24 The Department ofHealth has been requestedto make extra funding available and the initial proposalis for screening to be offered to men on or about their65th birthday.

EconomicsThe economics of population screening for abdomi-

nal aortic aneurysms on this scale have been analysed indetail by Collin.25 The cost of screening alone wouldamount to less than one million pounds per annum forthe whole of England and Wales or roughly £100 peraneurysm detected. An additional 4300 electiveoperations would be required but 1500 fewer emer-gency operations for ruptured aneurysms would benecessary each year. At £4000 per elective operationthe net additional cost for the operations would beabout £8 million. Each year around 20000 life yearswould be saved at a medical cost of £450 per qualityadjusted life year (QALY). This compares with anestimated cost of £4136 per QALY for the nationalbreast screening programme.26

Given the uncertain aetiology of the disease and itsessentially occult nature, neither attempts at preventionnor the introduction ofinnovative methods oftreatmentcan be expected to have much impact on the number ofdeaths from this cause. The essential requirement is todetect a higher proportion of lesions before rupturewhen most are asymptomatic, and from the evidencepresented here it is apparent that this objective is bothfeasible and affordable. If it is accepted that thecurrently high mortality from abdominal aorticaneurysm must be reduced, then it follows that there isa need for a national screening programme.

I Fowkes FGC, l\aclntyre CCA, Ruckley CV. Increasing incidence of aorticaneurysms in England and Wales. BM3' 1989;298:33-5.

2 Office of Population Censuses and Surveys. Mortality statistics, Englanid andWales. London: HMSO, 1984.

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3 Melton Ll, Bickerstaff LK, Hollier LH, Van-Peenen HJ, Lie Jr, PairoleroPC, et al. Changing incidence of abdominal aortic aneurysms. A populationbased study. AnmJ Epidemiol 1984;120:379-86.

4 Powell JT, Bashir A, Dawson S. Genetic variation on chromosome 16 isassociated with abdominal aortic aneurysm. Clin Sci 1990;78: 13-6.

5 Collin J, Murie J, Morris PJ. The Oxford experience of surgery for abdominalaortic aneurysm. A two year prospective analysis. Surg Gynecol Obstet1989;169:527.

6 Armour RH. Survivors of ruptured abdominal aortic aneurysm; the iceberg'stip. BMJ 1977;ii: 1055-7.

7 Ingoldby CJH, Wuianto R, Michell JE. Impact of vascular surgery oncommunity mortality from ruptured aneurysms. Br Surg 1986;73:551-3.

8 Johansson G, Swedenborg J. Ruptured abdominal aortic aneurysms: a study ofincidence and mortality. BrJSurg 1986;73:101-3.

9 Smith FCT, Grimshaw GM, Shearman CP, Hamer JD. Aortic aneurysmscreening in an urban community [abstract] Br3r Surg 1992;79:358.

10 O'Kelly TJ, Heather BP. General practice-based population screening forabdominal aortic aneurysms: a pilot study. BrJ Surg 1989;76:479.

11 Collin J, Walton J, Araujo L, Lindsell D. Oxford screening programme forabdominal aortic aneurysm in men aged 65-74 years. Lancet 1988;ii:613-5.

12 Scott RAP, Ashton H, Kay DN. Routine ultrasound screening in managementof abdominal aortic aneurysm. BM,J 1988;296:1709.

13 McGregor JC, Pollock JG, Anton HC. The value of ultrasonography in thediagnosis of abdominal aortic aneurysm. Scott MedJ 1975;20:133-7.

14 Ellis M, Powell JT, Greenhalgh RH. The limitations of ultrasonography insurveillance of small abdominal aortic aneurysms. BrJSurg 1991:78-614-6.

15 Turk KAD. The post mortem incidence of abdominal aortic aneurysm.Proceedings of the Royal Society ofMedicine 1%5;58:869-70.

16 Office of Population Censuses and Surveys. England and Wales. Mortalitystatistics: cause. London: HMSO, 1986.

.17 Collin J, Walton J. Is abdominal aortic aneurysm familial? BM3' 1989;299:49.18 Bengtsson H, Norrgard 0, Angquist KA, Ekberg 0, Oberg L, Bergqvist D.

Ultrasonic screening of the abdominal aorta among siblings of patients withabdominal aortic aneurysms. Br7 Surg 1989;76:589-91.

19 Bengtsson H, Ekberg D, Aspelin P, Kallero S, Bergqvist D. Ultrasoundscreening of the abdominal aorta in patients with intermittent claudication.Eurj Vasc Surg 1989;3:497-502.

20 Scott RAP, Ashton GLJ. Ultrasound screening of a general practice populationfor aortic aneurysm. Brj Surg 1986;73:318-23.

21 Szilagyi DE, Elliot JP, Smith RF. Clinical fate of the patient with asytnptomaticabdominal aortic aneurysm and unfit for surgical treatment. Arch Surg1972;104:600-6.

22 Bergqvist D, Bengtsson H. Is screening for abdominal aortic aneurysmsworthwhile? Ann Chir Gynaecol 1992;81:203-8.

23 Barodi JC, Palmaz JC, Barone HD. Transfemoral intraluminal graft ihn-plantation for abdominal aortic aneurysms. Ann Vasc Surg 1991;5:491-9.

24 Secretary of State for Health. The health of the nation. A strategy for health inEngland. London: HMSO, 1992.

25 Collin J. The value of screening for abdominal aortic aneurysm by ultrasound.In: Greenhalgh RM, Marrick JA, eds. The cause and management ofaneurysms. London: Saunders, 1990.

26 Blamey RW, Hardcastle JD. The early detection of cancer. In: Russell RCG,ed. Recent advances in surgery. 12. Edinburgh: Churchill Livingstone,1986:29.

(Accepted 30Julv 1992)

AIDS, ethics, and clinical trials

Institute of Medical Ethics Working Party on the Ethical Implications of AIDS

Institute of Medical EthicsWorking PartyMembers of the workingparty are listed at the end ofthis report.

Correspondence to:Dr K M Boyd, Institute ofMedical Ethics, RoyalInfirmary of Edinburgh,Edinburgh EH3 9YW

BMJ 1992;305:699-701

Asking a clinical scientist when he or she last read theDeclaration of Helsinki' is rather like asking a seasonedairline traveller when he or she last listened to thesafety announcement. The declaration sets out ethicalprinciples which no one seriously disputes and onwhich other authoritative statements'-' are essentiallycommentary. But the Declaration of Helsinki is some-times more difficult to put into practice than toreplicate on paper. Two of its principles, for example,mark out an area of possible moral conflict: "researchinvolving human subjects must conform to generallyaccepted scientific standards," and "concern for theinterests of the subject must always prevail over theinterest of science and society." AIDS research high-lights this possible conflict but also suggests new waysof resolving it.

"RESEARCH INVOLVING HUMAN SUBJECTS MUSTCONFORM TO GENERALLY ACCEPTED SCIENTIFICSTANDARDS"

The scientific gold standard today is the randomisedclinical trial. Scientists have found no more effectiveway to reduce bias, control variables, and establishpriorities among the available options. Alternativeswhich have been suggested-for example, "pros-pective studies without randomization, but with theevaluation of patients by uninvolved third parties,"or "prospective matched-pair analysis in whichpatients are treated in a manner consistent with theirphysician's views"'7-do not remove bias sufficiently.

"CONCERN FOR THE INTERESTS OF THE SUBJECT MUSTALWAYS PREVAIL OVER THE INTEREST OF SCIENCE ANDSOCIETY"

Many patients become subjects of research fromwhich they receive no direct benefit. The research maybe non-therapeutic or, as a result of randomisation in atherapeutic clinical trial, the patient may be given atreatment which turns out to be ineffective or not givenwhat turns out to be an effective treatment.A subject's failure to benefit directly need not mean

that concern for the interest of science and society hasprevailed over concern for that of the subject. Doctorshave a duty to avoid harm to their patients and to servetheir best interest. But they also have a duty to respect

the autonomy of patients as persons, who are the finalarbiters of what is in their own best interest. A patientmay have an altruistic interest in taking part in non-therapeutic research, or an interest in the possibility,however remote, of direct benefit. Informed consentmeans that the patient freely accepts the implicationsof the uncertainty principle which, scientifically as wellas ethically, justifies the study.

Is it ethically justifiable to invite patients, for whosecondition there is no existing treatment, to be random-ised to a new treatment or a placebo? Since a clinicaltrial implies some chance of the new treatment beingeffective have these patients, in their own interest, anyalternative to accepting? (British doctors, after all,have an alternative. If they judge that it is in theirpatient's best interest they can obtain the new treat-ment as an "innovative therapy.")4

This argument seems strongest when the newtreatment is designed to delay or arrest the progress ofa life threatening disease. But such treatment, un-fortunately, often carries the highest risks. For thepatient the new treatment could result in a shorter ormore distressing existence than no treatment. Insome clinical trials-for example, a recent cardiacarrhythmia suppression trial89- non-interventiongroups have actually had better survival rates. Askingthese patients if they are willing to be randomised to anew treatment or a placebo, then, is not offering thema choice which, in their own interests, they cannotrefuse. Here again, informed consent to the impli-cations of the uncertainty principle is the relevantethical criterion.

AIDS AND CLINICAL TRIALS IN THE UNITED STATES

For several decades most patients have implicitlyaccepted the logic of the uncertainty principle and, ifasked, have agreed to take part in clinical trials. But inthe past few years significant numbers of patients withHIV infection or AIDS have criticised this researchmethod, taken direct action to subvert it, and forcedresearchers and regulatory authorities to adopt newstrategies."' Some factors contributing to this arespecific to HIV infection and AIDS, to the UnitedStates, and to those initially infected there and inEurope. What is being learnt from this experience,however, has wider application.

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