DESIGN OF THE ABDOMINAL AORTIC-ANEURYSM DETECTION AND MANAGEMENT STUDY

Purpose: This study describes the design of an ongoing randomized tria l intended to determine which of two strategies is superior for managi ng small abdominal aortic aneurysms (AAA). Methods: Patients aged 50 t o 79 years with AAA 4.0 to 5.4 cm in diameter as determined by compute d tomography (CT) who are not at high surgical risk are randomized to either repair of the AAA, called ''immediate surgery,'' or follow-up o f the AAA with ultrasonography or CT every 6 months, reserving surgery for those aneurysms that enlarge to 5.5 cm, enlarge rapidly, or becom e symptomatic, called ''selective surgery.'' Results: The primary outc ome measure is all-cause death, and secondary outcome measures are AAA -related death, morbidity, and general health status. The study design calls for 1350 patients to be randomized and monitored for a mean of 5 years. A second objective of the study is to accurately define the p revalence and risk factors for AAA with use of information from the la rge screening program established to detect AAA for recruitment into t he randomized trial. Conclusions: By the end of 1993, 38,697 patients had been screened with ultrasonography, accounting for about three fou rths of new randomizations, and 330 patients had been enrolled (70% of the target rate).