Correcting for Body Surface Area Identifies the True Prevalence of Abdominal Aortic Aneurysm in Screened Women

Abstract

Recently, the prevalence of abdominal aortic aneurysm (AAA) using screening strategies based on elevated cardiovascular disease (CVD) risk was reported. AAA was defined as a diameter ≥30mm, with prevalence of 6.1% and 1.8% in men and women respectively, consistent with the widely reported AAA predominant prevalence in males. Given the obvious differences in body size between sexes this study aimed to re-evaluate the expanded CVD risk based AAA screening dataset to determine the effect of body size on sex specific AAA prevalence. Absolute (26 and 30mm) and relative (aortic size index [ASI] equals the maximum infrarenal aorta diameter (cm) divided by body surface area (m2), ASI≥1.5) thresholds were used to assess targeted AAA screening groups (n=4115) and compared with a self reported healthy elderly control group (n=800). Male AAA prevalence was the same using either the 30mm or ASI ≥1.5 aneurysm definitions (5.7%). In females, AAA prevalence was significantly different between the 30mm (2.4%) and ASI≥1.5 (4.5%) or the 26mm (4.4%) thresholds. The results suggest the purported male predominance in AAA prevalence is primarily an artefact of body size differences. When aortic size is adjusted for body surface area there is only a modest sex difference in AAA prevalence. This observation has potential implications in the context of the ongoing discussion regarding AAA screening in women.