Selective screening for abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) meets the criteria as a possible target for early detection by screening or case-finding, although the effectiveness of such an intervention has not yet been demonstrated. The purpose of this study was to estimate the increase in cost-effectiveness that would result from selectively screening individuals based on their risk of AAA. Data from a hospital-based case-control study involving 78 men with AAA (unruptured) and 99 male controls were used to derive a risk function based on age, cigarette smoking, high blood pressure, history of heart disease, body mass index and serum high-density lipoprotein, using logistic regression analysis. For each of the control subjects (assumed to be a representative sample of the general population of elderly men), the risk of AAA was estimated and multiplied by the expectation of life to give a measure of the potential benefit of screening. The proportion of the total potential benefit that would be obtained by screening only those with a given level of risk was estimated, and this was related to the proportion of the population screened. In order to obtain 80% of the total potential benefit among men, we found that it would be necessary to examine 52% of the elderly male population if using a risk function based on age alone; 35% would have to be screened if age and smoking were included; and 17% would require screening if all the risk factors were included. Selective screening for AAA appears to be a promising strategy, but a prospective study is required to demonstrate that the predictions are valid.