Ultrasound screening for abdominal aortic aneurysm in medicare beneficiaries

Ultrasound screening for abdominal aortic aneurysm (AAA) has been shown to be beneficial and cost-effective for men aged 65-74. However, most screening studies have been conducted in Europe and Australia, where attendance for screening was higher than the single large U.S. study involving only veterans. The prevalence of AAA in the U.S. general population is not well defined, nor is the best method of recruitment for screening. Letters of invitation for a free screening ultrasound for AAA were sent to 30,000 randomly selected Medicare beneficiaries from the hospital referral region of three university-affiliated hospitals without restriction by age, gender, or comorbidity. Attendance for screening was calculated by age, gender, and travel distance to the screening center. Telephone calls to a random sample of nonresponders were made to determine the reason for failure to attend. Prevalence of AAA by ultrasound and known risk factors for AAA (e.g., age, gender, smoking status) were determined. The attendance rate was 7% (2,005). Attendance was greater with male gender (p < 0.01), younger age (p < 0.05), and decreased travel distance to the screening center (p < 0.05). The primary reasons for failure to attend included incorrect address or vital status, poor health, and lack of interest. Prevalence of previously undetected AAA was 2.8% in men and 0.2% in women. AAA was predicted by smoking status and male gender (p < 0.01 for each). Unselected invitation of Medicare beneficiaries for ultrasound screening for AAA results in a low attendance and low yield of AAA. The prevalence estimates from this study may not reflect the entire Medicare population given the low attendance and may reflect the healthy habits of those most interested in screening. Patients should be selected for screening based on their suitability for repair if an AAA is found as well as their risk factors for AAA. The best method of recruitment for screening of those most at risk for AAA in the United States remains to be determined.