Performance validation of the ALPPS risk model

Background: Based on the International ALPPS registry, we have recently proposed two easily applicable risk models (pre-stage1 and 2) for predicting 90-day mortality in ALPPS but a validation of both models has not been performed yet. Methods: The validation cohort (VC) was composed of subsequent cases of the ALPPS registry and cases of centers outside the ALPPS registry. Results: The VC was composed of a total of 258 patients including 70 patients outside the ALPPS registry with 32 cases of early mortalities (12%). Development cohort (DC) and VC were comparable in terms of patient and surgery characteristics. The VC validated both models with an acceptable prediction for the pre-stage 1 (c-statistic 0.64, P = 0.009 vs. 0.77, P < 0.001) and a good prediction for the pre-stage 2 model (c-statistic 0.77, P < 0.001 vs. 0.85, P < 0.001) as compared to the DC. Overall model performance measured by Brier score was comparable between VC and DC for the pre-stage 1 (0.089 vs. 0.081) and pre-stage 2 model (0.079 vs. 0087). Conclusion: The ALPPS risk score is a fully validated model to estimate the individual risk of patients undergoing ALPPS and to assist clinical decision making to avoid procedure-related early mortality after ALPPS.