Facts and Not Fiction: The Small Aneurysm Trials do Not Justify Early Surgical Intervention

Eur J Vasc Endovasc Surg 28, 227 (2004) doi: 10.1016/j.ejvs.2004.05.010, available online at http://www.sciencedirect.com on

CORRESPONDENCE

Facts and Not Fiction: The Small Aneurysm Trials do Not Justify Early Surgical Intervention Debate is the cornerstone of progress and we welcome critical appraisal of our contribution to evidence-based medicine, the UK Small Aneurysm Trial.1 – 4 Professor Branchereau attempts to use the evidence we provided to make a case for early intervention for ‘good risk patients’ with all abdominal aortic aneurysms (AAA) greater than 5 cm in diameter.5 Such a strategy is not supported by evidence. In analyses of the UK Small Aneurysm Trial data, by subgroups of aneurysm size, age and gender, there were no clear-cut differences in results.1,4 Professor Branchereau selectively cites results in particular subgroups, without reference either to their imprecision or to whether they were convincingly different from other subgroups. Other support from Professor Branchereaus’s argument is based largely on misconception. First, the UK Small Aneurysm Trial was designed and powered to show the superiority of early surgery after 5-years of follow up. Randomisation of 1000 patients should have given us an 80% chance of showing a true difference in 5-year survival (29% mortality for early surgery and 38% mortality for surveillance patients).1 Second, the late survival results reported in 20024 included events for patients no longer followed up by trial protocol and hence data must be interpreted with due caution. Further, with respect to cause of death, at all time points the knowledge that a patient has AAA, is more likely to lead to a diagnosis of ruptured AAA in cases of sudden death. Third, Professor Branchereau has misquoted important results. The 5.8% surgical mortality rate reported was for all surgery (emergency and elective), not just elective surgery. The rupture rate for patients

within trial protocol was 1% per annum. The 1167 patients followed up for rupture outside the trial included a sizeable cohort ðn ¼ 100Þ with AAA diameter . 5.5 cm, where the crude rupture rate was 28% per annum. Nevertheless the overall rupture rate was only 2.2% per annum.3 The most persuasive support for the UK Small Aneurysm Trial results comes from the similar Aneurysm Detection and Management trial, where even with an operative mortality half of that in the UK trial, early surgery did not improve 5-year survival.6 UK Small Aneurysm Trial Management Committee 1

UK Small Aneurysm Trial Management Committee: F. G. R. Fowkes, R. M. Greenhalgh, J. T. Powell, C. V. Ruckley, S. G. Thompson with trial manager L. C. Brown. Department of Vascular Surgery, Charing Cross Hospital, Fulham Palace Road, London, UK

References 1 Branchereau A. Small aortic aneurysms: is evidence evident? Eur J Vasc Endovasc Surg 2004; 27:363–365. 2 The UK Small Aneurysm Trial Participants, Mortality results for randomised controlled trial of early elective surgery or ultrasonographic surveillance for small abdominal aortic aneurysms. Lancet 1998; 352:1649–1655. 3 Brown LC, Powell JT, for the UK Small Aneurysm Trial Participants. Risk factors for aneurysm rupture in patients kept under ultrasound surveillance. Ann Surg 1999; 230:289–296. 4 Small UK Aneurysm Trial Participants, Long-term outcomes of immediate repair compared with surveillance of small abdominal aortic aneurysms. New Engl J Med 2002; 346:1445–1452. 5 Branchereau A. Small aortic aneurysms: is evidence evident? Eur J Vasc Endovasc Surg 2004; 27:363–365. 6 Lederle FA, Wilson SE, Johnson GR et al. Immediate repair compaired with surveillance of small abdominal aortic aneurysms. New Engl J Med 2002; 346:1437–1444. Accepted 24 May 2004

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