The online version of this article (doi:10.1186/s13054-017-1673-6) contains supplementary material, which is available to authorized users.
The 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.
We 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.
The 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.
Both 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.
ClinicalTrials.gov identifier: NCT01422070. Registered 19 August 2011.
Additional file 1: Additional details on data collection. (DOCX 14 kb)13054_2017_1673_MOESM1_ESM.docx
Additional file 2: Additional details on statistical methods. (DOCX 16 kb)13054_2017_1673_MOESM2_ESM.docx
Additional file 3: Original and reassessed points of the items of SAPS 3 score. (DOCX 18 kb)13054_2017_1673_MOESM3_ESM.docx
Additional file 4: SMRs and Brier scores of the SAPS II and SAPS 3 scores, by reason for admission to ICU. (DOCX 11 kb)13054_2017_1673_MOESM4_ESM.docx
Additional file 5: Distribution of the SD of the center-specific Brier scores under the assumption that the calibration is the same in all centers for (a) the SAPS II score and (b) the SAPS 3 score. The vertical lines represent the observed SD of Brier score. (DOCX 24 kb)13054_2017_1673_MOESM5_ESM.docx
Additional file 6: SMRs and Brier scores of the SAPS II and SAPS 3 scores, by categories of health expenditure (percentage of GDP). (DOCX 12 kb)13054_2017_1673_MOESM6_ESM.docx
Additional file 7: Ethics committees. (DOCX 33 kb)13054_2017_1673_MOESM7_ESM.docx
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- Determinants of the calibration of SAPS II and SAPS 3 mortality scores in intensive care: a European multicenter study
Thomas V. Perneger
- BioMed Central
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