ArticlesMortality results for randomised controlled trial of early elective surgery or ultrasonographic surveillance for small abdominal aortic aneurysms
Introduction
Abdominal aortic aneurysms commonly remain symptomless until they rupture. Aneurysms are an important cause of sudden death1 and form a large part of the vascular surgical caseload.2 Necropsy studies and clinical studies have suggested that the risk of rupture accelerates with increasing aortic diameter.3, 4 Surgeons, therefore, generally recommend prophylactic repair of aneurysms of more than 6·0 cm in diameter (which is about three times larger than the normal aortic diameter). There is, however, uncertainty about whether prophylactic repair is the best management for smaller symptomless aneurysms of 4·0–5·9 cm in diameter. Ultrasonographic screening studies of the general population in the UK show that 1·5–3·0% of men older than 60 years have occult aneurysms in this size range.5, 6, 7, 8
There is currently no medical therapy that can prevent aneurysm growth and decrease the risk of rupture. The only available treatment for smaller abdominal aortic aneurysms is the insertion of a prosthetic aortic graft. Traditionally, surgery has been an elective open procedure with a 30-day operative mortality risk of 5–6%.9, 10 Endovascular repair has been introduced, but this technique is still under development and also has a high risk of procedure-associated mortality.11 Elective aneurysm surgery is, however, safer than emergency repair of a ruptured aortic aneurysm, for which the 30-day mortality is 40–50%.12, 13
It is not clear whether a policy of open surgical repair of small abdominal aortic aneurysms is preferable to a policy of surveillance, which has an higher risk of aneurysm rupture and death. Vascular surgeons in the UK, Canada, and the USA have been participating in three separate randomised trials to test the hypothesis that early, prophylactic elective surgery decreases the long-term mortality for patients with small abdominal aortic aneurysms (4·0–5·5 cm). This diameter range was selected by vascular surgeons in the UK, where the first trial started.14 The Canadian trial ended early because of inadequate recruitment (C William Cole, personal communication) and the US trial15 is continuing (Frank Lederle, personal communication). In the UK Small Aneurysm Trial,16 1090 patients were randomised between 1991 and 1995 to undergo early elective open surgical repair or regular ultrasonographic surveillance of aortic diameter. We report on the all-cause mortality results of the UK trial.
Section snippets
Methods
The methods have been described elsewhere.16 In 93 UK hospitals between September, 1991, and October, 1995, 1276 patients aged 60–76 years who were fit for elective surgery were identified as having symptomless (non-tender), infrarenal, abdominal aortic aneurysms of 4·0–5·5 cm in diameter. About half of these patients (610) were referred to vascular surgeons from another hospital clinic, 288 by their family physicians, 234 from screening programmes, 111 from hospitals not participating in the
Results
Of the 1090 patients (902 men and 188 women) who consented to randomisation, 563 (52%) were assigned to undergo early elective surgery and 527 (48%) to undergo ultrasonographic surveillance. Of the 563 patients in the early-surgery group, elective aneurysm repair with a prosthetic inlay graft was done in 517. In 452 (87%) of these patients, the operation was done within 5 months of randomisation. The median time to surgery was 1·8 months (IQR 1·1–3·6). In two further patients, emergency
Discussion
Our results show that elective surgical repair was not associated with a long-term survival advantage for patients with small, symptomless abdominal aortic aneurysms. Ultrasonongraphic surveillance provided a safe alternative method of management. The survival curves (figure 3) reflect the early attrition rate in the early surgery group, in which the 30-day surgical mortality was 5·8%. After 3 years, the survival curves crossed, but at 6 years the survival was 64% in both groups, which is
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Trial members and participants listed at end of paper