Study Suggests Use of Aortic Size Index May Improve AAA Repair Outcomes in Women
March 28, 2017—The Society for Vascular Surgery (SVS) announced that in a study published by Sarah E. Deery, MD, et al in Journal of Vascular Surgery (JVS), women appear to have worse mortality and morbidity outcomes than men after abdominal aortic aneurysm (AAA) repair (2017;65:1006–1013).
According to SVS, study investigators examined sex differences in 6,611 patients undergoing AAA repair registered in the National Surgical Quality Improvement Program database. The review of the data confirmed previous studies that had suggested higher morbidity and mortality in women after repair, even after adjusting for age, aortic diameter, and other medical conditions.
The investigators proposed that an explanation for this difference may be that women have smaller baseline aortic diameters given their overall smaller body size. They reanalyzed the data using the aortic size index (ASI) instead of aortic diameter. This index divides the aortic diameter by body surface area. In the SVS announcement, Lead Investigator Marc Schermerhorn, MD, said, “Adjusting for ASI reduces these (gender) differences, suggesting that ASI may be a better indicator threshold for AAA repair for female patients.”
As summarized in JVS, the targeted vascular module of the National Surgical Quality Improvement Program was queried to identify patients undergoing endovascular aneurysm repair (EVAR) or open repair for intact, infrarenal AAAs from 2011 to 2014. Univariate analysis was performed using the Fisher exact test and Mann-Whitney test. Multivariable logistic regression was used to account for differences in comorbidities, aneurysm details, and operative characteristics.
The investigators identified 6,611 patients (19% women) who underwent intact AAA repair (87% EVAR; 83% women vs 88% men; P < .001). Women were older (median age, 76 vs 73 years; P < .001), had smaller aneurysms (median, 5.4 vs 5.5 cm; P < .001), and had a higher incidence of chronic obstructive pulmonary disease (22% vs 17%; P < .001).
Among patients undergoing EVAR, women had longer operative times (median, 138 [interquartile range (IQR), 103–170] vs 131 [IQR, 106–181] minutes; P < .01) and more often underwent renal (6.3% vs 4.1%; P < .01) and lower extremity (6.6% vs 3.8%; P < .01) revascularization.
After open repair, women had shorter operative times (215 [IQR, 177–304] vs 226 [IQR, 165–264] minutes; P = .02), but women less frequently underwent lower extremity revascularization (3.1% vs 8.2%; P = .03). Thirty-day mortality was higher in women after EVAR (3.2% vs 1.2%; P < .001) and open repair (8% vs 4%; P = .04).
After adjusting for repair type, age, aneurysm diameter, and comorbidities, female sex was independently associated with mortality (odds ratio [OR], 1.7; 95% confidence interval [CI], 1.1–2.6; P = .02) and major complications (OR, 1.4; CI, 1.1–1.7; P < .01) after intact AAA repair.
However, after adjusting for ASI rather than for aortic diameter, the association between female sex and mortality (OR, 1.5; CI, 0.98–2.4; P = .06) and major complications (OR, 1.1; CI, 0.9–1.4; P = .24) was reduced.
The investigators concluded that women were at higher risk for 30-day death and major complications after intact AAA repair. Some of this disparity may be explained by differences in ASI, which should be further evaluated to determine the ideal threshold for repair, advised the investigators in JVS.