The study provides a more accurate assessment of the risk of aneurysm rupture without surgery and helps to define rescreening intervals for those with an enlarged aortic diameter.

The duration of exposure rather than the level of exposure appears to determine the risk of the development of an AAA in men older than 50 years. The slow decline of risk after the cessation of smoking and the higher relative risk for small compared with large aneurysms suggest that smoking is an initiating event for the condition.

The prevalence of small AAA ranges between 3 and 8 per cent. The incidence of asymptomatic AAA seems to be increasing, although exact incidence estimates vary. The most important risk factors for AAA are male sex, age, family history and smoking. Hypertension is associated with a mildly increased risk, but diabetes is not associated with any increase. Primary prevention of AAA is not a realistic option. There is no evidence of an effective medical treatment to prevent growth of small AAAs, although trials with propranolol are under way. The only intervention to prevent death from aneurysm is elective repair of the asymptomatic lesion. Screening for asymptomatic AAA can reduce the incidence of rupture. However, further studies are needed to determine the cost effectiveness of screening compared with that of other health programmes.

Screening for asymptomatic AAAs can reduce the incidence rate of RAAAs by 49% (95% CI, 3% - 74%).

One hundred and twenty-four limbs in patients suffering from intermittent claudication were studied over 10 months. Changes in ankle pressure and treadmill exercise tolerance over the period were compared between two groups, one of patients who continued to smoke (group 1) and the other of those who gave up (group 2). Resting ankle systolic pressure fell in smokers' limbs by a mean of 10.2 mmHg (t = 3.56, P less than 0.001), and rose in those patients who stopped smoking by a mean 8.7 mmHg (P = n.s.). Ankle pressures after exercise and maximum treadmill walking distance did not change in smokers but significantly improved in past smokers. Stopping cigarette smoking increased the chance of improvement in ankle pressure and exercise tolerance in intermittent claudication.