Variability in Short-term Mortality Following Repair of Ruptured Abdominal Aortic Aneurysms Across Centers and Physicians

Background Variation in the care management of repairs for ruptured infrarenal abdominal aortic aneurysms (rAAA) between centers and physicians, e.g., the procedural volumes may explain differences in mortality outcomes. First, we quantified the center and physician variability associated with 30- and 90-day mortality risk following open (rOSR) and endovascular (rEVAR) aneurysm repair. Second, we explored wheter part of this variability was attributable to procedural volume at the center and physician level. Methods Two cohorts including rOSR and rEVAR procedures between 2013-2019 were analyzed from the Vascular Quality Initiative database. Thirty- and 90-day all-cause mortality was derived from linked Medicare claims data. The median odds ratio (MOR, median mortality risk from low- to high-risk cluster) and intraclass correlation (ICC, variability attributable to each cluster) for 30- and 90-day mortality risk associated with center and physician variability were derived using patient-level adjusted multilevel logistic regression models. Procedural volume was calculated at the center and physician levels and stratified by quartiles. The models were sequentially adjusted for volumes, and the difference in ICC (without vs. with accounting for volume) was calculated to describe the center and physician variability in mortality risk attributable to volumes. Results We included 450 rOSRs (mean age=74.5±7.6 years; 23.5% female) and 752 rEVARs (76.4±8.4 years; 26.1% female). Following rOSRs, the 30- and 90-day mortality rates were 32.9% and 38.7%. No variability across centers and physicians was noted (30- and 90-day MORs ≈ 1 and ICCs ≈ 0%). Neither center nor physician volume was associated with 30-day(P=.477 and P=.796) or 90-day mortality (P=.098 and P=.559). Following rEVAR, the 30- and 90-day mortality rate was 21.3% and 25.5%, respectively. Significant center variability (30-day MOR=1.82 95%CI 1.33-2.22 and ICC=11% 95%CI 2%-36%; 90-day MOR=1.76 95%CI 1.37-2.09 and ICC=10% 95%CI 3%-30%), but negligeable variability across physicians (30- and 90-day MORs≈1 and ICCs ≈ 0%) were noted. Neither center nor physician volume was associated with 30- (P=.076 and P=.336) nor 90-day mortality risk (P=.066 and P=.584). The center variability attributable to procedural volumes was negligeable (difference in ICCs: 1% for 30-day; 0% for 90-day mortality). Conclusion Variability in practice from center-to-center was associated with short-term mortality outcomes in rEVAR, but not for rOSR. Physician variability was not associated with short-term mortality for rOSR or rEVAR. Annualized center and physician volumes did not significantly explain these associations. Further work is needed to identify center-level factors affecting the quality of care and outcomes for ruptured AAA.