External validation of the Simplified Acute Physiology Score (SAPS) 3 in a cohort of 28,357 patients from 147 Italian intensive care units.

OBJECTIVE: To evaluate the SAPS 3 score predictive ability of hospital mortality in a large external validation cohort. DESIGN: Prospective observational study. SETTING AND PATIENTS: A total of 28,357 patients from 147 Italian ICUs joining the Project Margherita national database of the Gruppo italiano per la Valutazione degli interventi in Terapia Intensiva (GiViTI). INTERVENTIONS: None. MEASUREMENT: Evaluation of discrimination through ROC analysis and of overall goodness-of-fit through the Cox calibration test. MAIN RESULTS: Although discrimination was good, calibration turned out to be poor. The general and the South-Europe Mediterranean countries equations overestimated hospital mortality overall (SMR values 0.73 with 95% CI 0.72-0.75 for both equations) and homogeneously across risk classes. Overprediction was confirmed among important subgroups, with SMR values ranging between 0.47 and 0.82. CONCLUSIONS: The result strictly supported by our data is that the SAPS 3 score calibrates inadequately in a large sample of Italian ICU patients and thus should not be used for benchmarking, at least in Italian settings.