Modified Harborview Risk Score improves ease in predicting mortality after ruptured abdominal aortic aneurysm repair

Validation of Harborview Risk Score for Ruptured Abdominal Aortic Aneurysms in a 22-Year Retrospective Single- Centre Experience

BACKGROUND

Among all the published risk scores, the Harborview Risk Score (HRS) is the only one that relies exclusively on preoperative variables that can be easily assessed at the bedside (age >76 years, creatinine concentration >2.0 mg/dL, systolic blood pressure ever <70 mm Hg and pH < 7.2 or international normalized ratio >1.8). This study has the aim of retrospectively evaluating the population of the ASST Grande Ospedale Metropolitano Niguarda (Milan) the accuracy of the HRS in Italy and of the modified Harborview Risk Score (mHRS) for the first time in Italy.

METHODS

A single-center, retrospective, observational study was performed. Information on patients treated for ruptured abdominal aortic aneurysms (rAAAs) between January 2002 and March 2024 at the ASST Grande Ospedale Metropolitano Niguarda, Milan (Italy) were collected.

RESULTS

Of the 180 patients treated for rAAA in our hospital during the 22-year study period, 158 met inclusion criteria for the HRS and 145 for the mHRS. Observed 30-day mortality using the HRS was 8.3%, 24.1%, 47%, 54.5%, and 100%, respectively, for a score from 0 to 4 (P value < 0.001). For the mHRS the 30-day mortality observed was 13.2%, 26.7%, 36.4%, 58.8%, and 100%, respectively, for a score from 0 to 4 (P value < 0.001). Receiver operating characteristic analysis revealed a slightly higher ability of the HRS to predict 30-day death (area under the curve = 0.732) than the mHRS (area under the curve = 0.682).

CONCLUSION

The HRS can accurately predict 30-day mortality after repair of rAAAs, with a higher accuracy for the HRS than the mHRS. These scores represent valuable tools that may guide the clinical decision-making process and help predict futility in the preoperative setting for this morbid disease.

External Validation of Eight Ruptured Abdominal Aortic Aneurysm Mortality Prediction Models Demonstrates Limited Predictive Accuracy

OBJECTIVE

Over a dozen ruptured abdominal aortic aneurysm (rAAA) mortality risk prediction models currently exist; however, lack of external validation limits their applicability. This study aimed to evaluate the accuracy of eight common rAAA mortality risk prediction models in a large, contemporary, external validation cohort.

METHODS

A retrospective review of rAAA repairs at a multicentre integrated regional healthcare system with large central quaternary referral facility (2010 - 2020) was performed. Eight models were used to predict 30 day post-operative death, including the Updated Glasgow Aneurysm Score (GAS), Vascular Study Group of New England rAAA Risk Score, Harborview Pre-operative rAAA Risk Score, Modified Harborview Risk Score, Vancouver Scoring System (VSS), Artificial Neural Network Score, Dutch Aneurysm Score, and Edinburgh Ruptured Aneurysm Score. The models were assessed for discrimination, calibration, and clinical utility using receiver operating characteristic curves (area under the curve [AUC]), Hosmer-Lemeshow χ2 test, Brier scores, and decision curve analysis. The proportion of unexpected survivors (survival despite > 80% predicted 30 day death) to expected deaths was compared across calculators, and both groups were compared using the model demonstrating the highest unexpected survival frequency.

RESULTS

Three hundred and fifteen rAAA repairs were included (mean age 73.6 ± 10.0 years; 72.1% male; 49.8% open repair) with a 30 day mortality rate of 32.1%. Three models had fair discrimination (AUC ≥ 0.70), with GAS having the highest AUC (0.74, 95% confidence interval 0.68 - 0.79). All models demonstrated poor to adequate calibration. Using VSS, unexpected survivors (n = 25) had less pre-operative shock (72% vs. 96%; p = .050) and statistically significantly less coagulopathy (median international normalised ratio 1.2 [interquartile range 1.1, 1.5] vs. 1.8 [1.3, 2.2]; p = .015) compared with expected deaths (n = 23).

CONCLUSION

Current rAAA risk prediction models demonstrated only fair discrimination and poor to adequate calibration. These findings suggest that existing risk prediction models have not sufficiently captured important physiological characteristics associated with rAAA death and should be applied cautiously to clinical practice.

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 = 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.