Abstract
BACKGROUND: This study aimed to assess the performance of the Simplified Acute Physiology Score 3 (SAPS 3) as a predictor of ICU mortality in critically ill patients of different case mixes admitted to an intensive care unit. METHODS: This retrospective cohort study was performed from January 2011 to August 2013 in the intensive care unit of a private tertiary referral center in the Philippines. Predicted ICU mortality was calculated using the SAPS 3 global model. Observed versus predicted mortality rates were compared, and the standardized mortality ratio (SMR) was calculated. The discrimination and calibration characteristics of the SAPS 3 system to predict ICU mortality were assessed. RESULTS: A total of 2,426 patients were included. The observed ICU mortality was 277 (11.42%). The SAPS 3 global model had fair to good discrimination with an area under the receiver operating characteristic curve of 0.80 (CI 0.78-0.81). Good calibration was seen with the Hosmer-Lemeshow goodness of fit at Ĉ = 11.51 (p = 0.175). Standardized mortality ratio was 0.36 (0.26-0.81). CONCLUSION: The global SAPS 3 prediction model showed fair to good discrimination and good calibration in predicting mortality in our intensive care unit. Different levels of discrimination and calibration across the different subgroups analyzed suggest that overall ICU performance seemed to be affected by case mix variations.