External Validation of Traditional and Modified Harborview Risk Scores for Ruptured Abdominal Aortic Aneurysm 30-day Mortality Prediction

Background: A critical issue in the preoperative assessment of a patient with a ruptured abdominal aortic aneurysm (rAAA) is death risk prediction. The traditional and modified Harborview Risk Score (tHRS and mHRS) consider readily available variables to estimate 30-day mortality. The aim of the study was to validate tHRS and mHRS in a rAAA external population. Methods: Consecutive patients undergoing rAAA repair from January 2012 to January 2024 at a tertiary Vascular Surgery Center were retrospectively reviewed. The scores were calculated for each patient; receiver operating characteristic curves (ROC), area under the curve (AUC) with 95% confidence intervals (CIs) and calibration plots were built to evaluate discrimination and calibration. Furthermore, the relationship of mortality with score variables was updated running a multivariate logistic model, and then applied to one thousand bootstrap samples. Results: One hundred and five patients treated for rAAA (97 males, 92.4%) were included in the study (77 +/- 8.5 years). An endovascular repair (rEVAR) was performed in 35 patients (3 women, 80 +/- 9.0 years) while an open repair (rOAR) in 70 patients (5 women, 75 +/- 8.0 years). The 30-day mortality rate was 31.4%, (33/105), 25.7% (9/35), and 34.3% (24/70) for rEVAR and rOAR, respectively (p 0.5). Eight patients (7.6%) were on therapy with warfarin at the time of admission. AUC for tHRS was 0.56 while AUC for mHRS was 0.68 (DeLong test 1/4 0.29). The tHRS' calibration showed underestimation for patients with predicted mortality <25% and overestimation for the remaining; for mHRS, the predictions were well calibrated for patients with estimated mortality <40% with overprediction afterward. The model update demonstrated that the wider effects are due to the interaction between the HRS factors. Conclusions: tHRS and mHRS showed limited prediction capability with 30-day mortality overestimation in an external validation, raising many concerns about their extended and systematic application. Interaction between factors should be taken into account to enhance the score's performance, especially in high risk patients.