Multicenter Registry Validation of the Modified Harborview Risk Score for Risk Stratification in Ruptured Abdominal Aortic Aneurysm

BACKGROUND: The modified Harborview Risk Score (mHRS) has been proposed as a bedside tool to stratify operative risk in patients with ruptured abdominal aortic aneurysms (rAAA), but its performance across operative strategies in contemporary multicenter settings remains incompletely characterized. METHODS: A retrospective cohort analysis was performed using the 2012-2022 American College of Surgeons National Surgical Quality Improvement Program Targeted endovascular aneurysm repair (EVAR) dataset. Adult patients undergoing open surgical repair (OSR) and EVAR of rAAA were included. The mHRS was calculated by assigning 1 point for age >76 years, creatinine >2 mg/dL, international normalized ratio >1.8, and systolic blood pressure <70 mm Hg. Multivariable regression and Royston-Parmar flexible parametric models were constructed to assess risk-adjusted outcomes stratified by mHRS. RESULTS: Among 2,291 patients, 55.8% underwent EVAR, and 44.2% underwent OSR. The distribution of the mHRS was similar between groups, with median of 1 (1-2) in both cohorts (P = 0.007). After multivariable adjustment, each point increase in the mHRS with OSR (reference: EVAR) yielded higher odds of mortality and complications, including aneurysm hemorrhage (all P < 0.001). When assessed across the mHRS stratum, the risk-adjusted mortality progressively increased for both modalities, with EVAR demonstrating improved outcome at each mHRS level compared to OSR. Time-to-event analysis demonstrated that the decline in freedom from mortality at 30 days was more pronounced following OSR compared to EVAR, particularly at higher mHRS (≥3). CONCLUSION: Our findings using the mHRS suggest that higher scores are associated with increased morbidity and mortality following OSR and EVAR for rAAA, with EVAR demonstrating more favorable outcomes across risk strata.