Trends and Outcomes of Elective Abdominal Aortic Aneurysm Repair in California State 2016 to 2022

Abstract

Objective:

To describe statewide trends in elective intact abdominal aortic aneurysm (AAA) repair in California (2016-2022) and to evaluate hospital-level volume-outcome relationships for endovascular aneurysm repair (EVAR) and open surgical repair (OSR) during 2019 to 2022.

Methods:

Retrospective analysis of the California Inpatient Mortality Indicators. The primary outcome was 30-day crude mortality; the 2022 risk-adjusted mortality rate (RAMR) served as a benchmark. Hospitals were aggregated across 2019 to 2022. Associations between hospital volume and mortality were tested with Spearman correlation, data-driven threshold scans, and overdispersion-adjusted binomial funnel plots with outlier flagging restricted to hospitals with ≥30 procedures. Sensitivity analyses excluded hospitals with <10 cases and excluded 2020.

Results:

From 2016 to 2022, there were 10 464 elective AAA repairs statewide. Since the coding split in 2019, EVAR has comprised ~92% of cases annually. Across 2019 to 2022, there were 6882 EVARs (53 deaths; crude mortality 0.77%) and 625 OSRs (42 deaths; 6.72%). In 2022, RAMR was 0.48% for EVAR and 4.43% for OSR. The highest-volume quartiles performed 55% of statewide cases for both modalities. For OSR, volume was not associated with mortality (ρ=0.15; p=0.27), no discrete volume threshold was identified, and no high- or low-mortality outliers were detected at ≥30 cases. For EVAR, volume correlated positively with crude mortality (ρ=0.36; p<0.001); no robust cut-point emerged; and a small number of high-mortality outliers appeared at the 95% limits and none at 99.8% (≥30 cases). Sensitivity analyses were concordant. The positive EVAR correlation likely reflects higher-risk case-mix at referral centers rather than a detrimental effect of volume.

Conclusions:

Contemporary elective EVAR in California demonstrates uniformly low mortality with few outliers and no hospital-volume threshold. The OSR outcomes are more variable, yet hospital volume is not associated with mortality. These findings support broad access to EVAR with routine outcomes-based surveillance and suggest that any concentration of open repair should be guided by demonstrated outcomes rather than arbitrary minimum-volume mandates.

Clinical Impact

This study provides actionable guidance for service design and referral. Elective endovascular aneurysm repair (EVAR) shows uniformly low mortality across hospitals, so access can remain broad; quality efforts should focus on continuous audit and rapid remediation of the rare high-mortality outliers identified by funnel monitoring. Open repair exhibits wider variability without a defensible volume cutoff; therefore, complex or open-eligible cases should be preferentially directed to teams with demonstrated outcomes rather than to centers meeting arbitrary case counts. Programs should formalize escalation and transfer pathways for open repair, maintain surgeon competence through targeted case concentration and cross-site coverage, and track outcomes with risk-adjusted dashboards. For patients, counseling can emphasize excellent early safety with EVAR and selective use of open surgery in experienced hands. Health systems can allocate resources toward EVAR capacity, surveillance infrastructure, and preservation of open aortic expertise instead of enforcing rigid volume minimums.