Sex-Based Differences in Outcomes Following Endovascular Repair of Unruptured Abdominal Aortic Aneurysms by Size

Background Abdominal aortic aneurysm (AAA) size thresholds for elective endovascular aneurysm repair (EVAR) remain primarily based on rupture risk and historical data, with limited validation in the modern endovascular era. In particular, the procedural risk trajectory across the spectrum of aortic diameters and the relevance of sex-specific thresholds remains poorly defined. Methods A retrospective cohort analysis was performed using the 2012–2022 American College of Surgeons National Surgical Quality Improvement Program (NSQIP) Targeted EVAR dataset. Adult patients undergoing elective EVAR for asymptomatic, unruptured AAA were included. Restricted cubic spline modeling identified sex-specific aneurysm diameters associated with increased major adverse events (MAE), defined as 30-day mortality or major complications. Patients were stratified by spline-derived diameter thresholds. Risk-adjusted associations between aneurysm size and perioperative outcomes were evaluated using multivariable logistic regression with LASSO-based covariate selection. Results Among 13,626 patients undergoing elective EVAR for asymptomatic, unruptured AAA, 18.1% were female. Female patients underwent repair at smaller median aortic diameters than male patients (5.4 [5.0–5.8] vs 5.5 [5.2–6.0] cm) but demonstrated a higher aortic size index (3.3 [2.9–3.7] vs 2.9 [2.6–3.2] cm/m 2 ). Sex-specific spline analyses identified inflection points for procedural risk at 5.3 cm in males and 5.2 cm in females. Repair at or above these thresholds was associated with higher rates of MAE in males (12.1% vs 9.2%) and females (21.9% vs 16.1%). Among females, above-threshold repair was also associated with higher 30-day mortality (2.4% vs 1.1%), greater transfusion requirement (12.1% vs 6.7%), and longer postoperative LOS (2 [1–3] vs 1 [1–2] days). After risk adjustment, aneurysm diameter at or above the spline-derived threshold remained independently associated with higher odds of MAE and prolonged hospital LOS in both sexes (all P<0.05), with no difference in risk-adjusted 30-day readmission. Conclusions Spline-derived thresholds revealed earlier onset of procedural risk than current guideline cutoffs for both sexes. Incorporating sex-specific, empirically derived risk markers into operative decision-making frameworks may improve timing of elective EVAR and enhance perioperative outcomes.