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

Abstract

WHAT THIS PAPER ADDS AAA is widely reported as having a significantly higher prevalence in males. This study adds to a body of evidence suggesting that sex differences in AAA prevalence are largely an artefact of the application of a single (male derived) absolute size threshold. Any discussion on the retention or future development of AAA screening programmes must use appropriate sex specific prevalence rates in order to provide a balanced and equitable consideration.Objective: 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 !30 mm, 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. Methods: Absolute (26 and 30 mm) and relative (aortic size index [ASI] equals the maximum infrarenal aorta diameter (cm) divided by body surface area (m 2 ), ASI ! 1.5) thresholds were used to assess targeted AAA screening groups (n ¼ 4115) and compared with a self reported healthy elderly control group (n ¼ 800). Results: Male AAA prevalence was the same using either the 30 mm or ASI !1.5 aneurysm definitions (5.7%). In females, AAA prevalence was significantly different between the 30 mm (2.4%) and ASI ! 1.5 (4.5%) or the 26 mm (4.4%) thresholds. Conclusion: 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.

A large proportion of patients with small ruptured abdominal aortic aneurysms are women and have chronic obstructive pulmonary disease

“…Here we report, as has previously been reported by Lo et al, that ASI is similar in men and women at rupture [22]. If an aneurysm definition that is based on ASI, instead of Dmax, is used, the prevalence of AAAs in women and men are almost equal [44]. The optimal policy for personalized surveillance cannot be suggested based on the current study, but factors such as ASI and PWRI should further be investigated, preferably in a prospective trial.…”

Long-Term Follow-Up of Men Invited to Participate in a Population-Based Abdominal Aortic Aneurysm Screening Program

“…28 –30 An adjunct to just measuring AD could be to use the ASI. 15,17,31 Our data suggest that AAA patients with ASI <1.5 could be followed-up at less frequent intervals (3-4 years), but an ASI >2.0 could be followed-up using the present intervals. To use ASI in surveillance programs instead of only AD cannot be generally recommended at this time but should be investigated further.…”

“…15,17 Similar data from New Zealand confirm that this consideration benefits more correct estimations, which presumably is most important for “smaller persons” (women vs men). 31 By introducing a more individualized approach, this could also influence and decrease the number of treated persons (tall men) with a low ASI, but a large maximum diameter.…”

A Methodology to Quantify the Geometrical Complexity of the Abdominal Aortic Aneurysm

“…In the literature, body size information (i.e. height and weight) have been reported to influence and explain reasons for gender differences and are often employed in such comparisons 16,17 . Nevertheless, because such data were not available herein, all dimensional variables were indexed to (i.e.…”