Hospital aneurysm caseload, open or endovascular technique, and 90-day mortality after repair of intact abdominal aortic aneurysm

Background The association between hospital caseload and surgical mortality, including in vascular surgery, remains debated. Randomized trials have reported lower postoperative mortality after endovascular aneurysm repair (EVAR) than after open repair for intact abdominal aortic aneurysm (IAAA), although this has not been independently demonstrated across studies. We therefore investigated whether higher hospital abdominal aortic aneurysm (AAA) caseload or greater use of EVAR was associated with lower 90-day mortality in an unselected nationwide cohort of IAAA (unruptured aneurysm involving the abdominal aorta) undergoing repair. Methods This retrospective observational cohort study included 4,868 patients who underwent IAAA repair over 5 years, identified from a prospective vascular registry covering all vascular units in Sweden. Data on age, sex, heart disease, prior heart failure, pulmonary disease, kidney disease, frailty, and operative urgency were obtained from multiple sources and analyzed in relation to 90-day mortality using logistic regression. Each patient was assigned a hospital caseload value (HCV), defined as the annual number of ruptured and unruptured AAA repairs performed at the treating hospital, and a hospital EVAR proportion value (HEV), defined as the proportion of IAAA repairs performed with EVAR. Results Across vascular units, HCV ranged from 8.4 to 101 and HEV from 0 to 0.97. Overall, 90-day mortality was 2.4% (95% confidence interval [CI], 2.0%–2.9%). In adjusted analyses, neither HCV nor HEV was associated with 90-day mortality (odds ratio [OR], 1.04; 95% CI, 0.89–1.21; P=.63 and OR, 1.06; 95% CI, 0.76–1.49; P=.73, respectively), and no threshold effect was identified for either caseload or EVAR proportion with respect to 90-day mortality. Male sex was associated with lower 90-day mortality (OR, 0.56; 95% CI, 0.37–0.85; P=.007), whereas heart disease (OR, 1.47; 95% CI, 1.00–2.18; P=.05), pulmonary disease (OR, 1.69; 95% CI, 1.14–2.50; P=.009), and unplanned repair of symptomatic aneurysm (OR, 2.28; 95% CI, 1.12–4.64; P=.023) or emergency repair (OR, 2.52; 95% CI, 1.41–4.49; P=.002) were associated with higher 90-day mortality. Conclusion In this nationwide cohort, neither higher hospital AAA caseload (roughly more than 10 annual cases) nor greater use of EVAR for IAAA repair was associated with lower postoperative 90-day mortality.