Prospective validation of the Israeli Score for the prediction of common bile duct stones in patients with acute calculous cholecystitis

Background: Existing guidelines for predicting common bile duct stones (CBDS) are not specific for acute calculous cholecystitis (ACC). This paper is a posthoc analysis of the S.P.Ri.M.A.C.C study aiming to prospectively validate on a large independent cohort of patients the Israeli Score (IS) in predicting CBDS in patients with ACC. Methods: The S.P.Ri.M.A.C.C. study is an observational multicenter prospective study endorsed by the World Society of Emergency Surgery (WSES). Between September 1st, 2021, and September 1st, 2022, 1201 participants were included. The Chi-Square test was used to compare categorical data. A Cochran-Armitage test was run to determine whether a linear trend existed between the IS and the presence of CBDS. To assess the accuracy of the prediction model, the receiver operating characteristic (ROC) curve was generated, and the area under the ROC curve (AUC) was calculated. Logistic regression was run to obtain Odds Ratio (OR). A two-tailed p < 0.05 was considered statistically significant. Results: The rate of CBDS was 1.8% in patients with an IS of 0, 4.2% in patients with an IS of 1, 24.5% in patients with 2 and 56.3% in patients with 3 (p < 0.001). The Cochran-Armitage test of trend showed a statistically significant linear trend, p < 0.001. Patients with an IS of 3 had 64.4 times (95% CI 24.8-166.9) higher odds of having associated CBDS than patients with an IS of 0. The AUC of the ROC curve of IS for the prediction of CBDS was 0.809 (95% CI 0.752-0.865, p < 0.001). By applying the highest cut-off point (3), the specificity reached 99%, while using the lowest cut-off value (0), the sensitivity reached 100%. Conclusion: The IS is a reliable tool to predict CBDS associated with ACC. The algorithm derived from the IS could optimize the management of patients with ACC.