• Antoine Poncet, Thomas V Perneger, Paolo Merlani, Maurizia Capuzzo, and Christophe Combescure.
• Clinical Research Center, Faculty of Medicine, University of Geneva, Geneva 4, 1211, Geneva, Switzerland.
• Crit Care. 2017 Apr 4; 21 (1): 85.

BackgroundThe aim of the Simplified Acute Physiology Score (SAPS) II and SAPS 3 is to predict the mortality of patients admitted to intensive care units (ICUs). Previous studies have suggested that the calibration of these scores may vary across countries, centers, and/or characteristics of patients. In the present study, we aimed to assess determinants of the calibration of these scores.MethodsWe assessed the calibration of the SAPS II and SAPS 3 scores among 5266 patients admitted to ICUs during a 4-week period at 120 centers in 17 European countries. We obtained calibration curves, Brier scores, and standardized mortality ratios. Points attributed to SAPS items were reevaluated and compared with those of the original scores. Finally, we tested associations between the calibration and center characteristics.ResultsThe mortality was overestimated by both scores: The standardized mortality ratios were 0.75 (95% CI 0.71-0.79) for the SAPS II score and 0.91 (95% CI 0.86-0.96) for the SAPS 3 score. This overestimation was partially explained by changes in associations between some items of the scores and mortality, especially the heart rate, Glasgow Coma Scale score, and diagnosis of AIDS for SAPS II. The calibration of both scores was better in countries with low health expenditures. The between-center variability in calibration curves was much greater than expected by chance.ConclusionsBoth scores overestimate current mortality among European ICU patients. The magnitude of the miscalibration of SAPS II and SAPS 3 scores depends not only on patient characteristics but also on center characteristics. Furthermore, much between-center variability in calibration remains unexplained by these factors.Trial RegistrationClinicalTrials.gov identifier: NCT01422070 . Registered 19 August 2011.

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