External validation of the SHARPEN score for predicting in-hospital mortality in infective endocarditis

Background Risk stratification of infective endocarditis (IE) using IE-specific variables remains limited. In this study, we evaluated SHARPEN in an Italian cohort and performed an exploratory paired comparison with baseline Sequential Organ Failure Assessment (SOFA) score. Methods We performed a retrospective study of consecutive adults with definite IE hospitalized at a tertiary center from 2000 to 2021.Primary endpoint was all-cause in-hospital mortality. Discrimination was assessed by ROC curves, calibration by Brier score, calibration intercept and slope, Hosmer–Lemeshow test, and decile-based plots. The optimal threshold was identified using the Youden index. A prespecified multivariable model including SHARPEN, hemoglobin, INR, and pre-existing heart failure was evaluated. Baseline SOFA was compared with SHARPEN in paired complete-case subset. Results 245 patients were included. In-hospital mortality occurred in 44 (18%). Non-survivors had higher SHARPEN scores (median 11 vs. 9,p < 0.001). The score showed good discrimination (AUC 0.748;95%CI0.660–0.834) and acceptable calibration (Brier 0.1269; Hosmer–Lemeshow p=0.458), with an optimal threshold of 11, yielding sensitivity 0.703, specificity 0.737, and NPV 0.918. A simple multivariable model combining SHARPEN with hemoglobin, INR, and chronic heart failure significantly improved discrimination (AUC 0.859; 95%CI0.796–0.921). Baseline SOFA was available in 75 patients (20 deaths); in this selected paired subset, AUCs were 0.759 (95%CI0.625–0.893) for SHARPEN and 0.878 (95%CI0.788–0.968) for SOFA. Conclusions The SHARPEN score demonstrated reproducible discrimination for predicting in-hospital mortality in IE in our cohort. The exploratory SOFA comparison did not establish superiority. SHARPEN could serve as an adjunct to multidisciplinary assessment rather than a stand-alone decision tool.