Objective: Current screening recommendations for abdominal aortic aneurysm (AAA) target >3-cm diameter aneurysms in ever-smoking 65- to 75-year-old males. However, more than 50% of AAA ruptures occur in individuals outside this patient cohort, and only a subset of AAAs detected are large enough to warrant surgery. In this analysis, we evaluated more than 3 million screened individuals and developed a scoring tool to identify ≥5-cm diameter AAAs in the entire population at risk.
Methods: Between 2003 and 2008, demographics and risk factors were collected from 3.1 million people undergoing ultrasound screening for AAA by Life Line Screening, Inc. Using multivariable logistic regression analysis, we identified risk factors and developed a scoring system to predict the presence of ≥5-cm diameter AAAs.
Results: Smoking had a profound influence on the risk of AAA, which increased with number of cigarettes smoked and years of smoking, and decreased following smoking cessation. Novel findings included a protective effect of exercise, normal weight, and Black/Hispanic race/ethnicity. Using these and other factors, the scoring system provided good predictive accuracy (C-statistic = 0.82), when tested against the validation subset of the study cohort. The model predicts the presence of 121,000 ≥5 cm AAA in the US population (prevalence: 0.14%). Demonstrating the inadequacy of the current screening recommendations, only 35% of these aneurysms were among males aged 65 to 75 years.
Conclusions: Based on the largest cohort of patients ever screened for AAA, we developed a screening strategy that can identify large AAAs in a broad population of individuals at risk.