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. 2017 Oct 30;12(10):e0187122.
doi: 10.1371/journal.pone.0187122. eCollection 2017.

Derivation and validation of a preoperative risk model for postoperative mortality (SAMPE model): An approach to care stratification

Luciana Cadore Stefani  1   2   3   4 , Claudia De Souza Gutierrez  2   3 , Stela Maris de Jezus Castro  5 , Rafael Leal Zimmer  3 , Felipe Polgati Diehl  2 , Leonardo Elman Meyer  2 , Wolnei Caumo  1   2   3   4
Affiliations

Derivation and validation of a preoperative risk model for postoperative mortality (SAMPE model): An approach to care stratification

Luciana Cadore Stefani et al. PLoS One. .

Abstract

Ascertaining which patients are at highest risk of poor postoperative outcomes could improve care and enhance safety. This study aimed to construct and validate a propensity index for 30-day postoperative mortality. A retrospective cohort study was conducted at Hospital de Clínicas de Porto Alegre, Brazil, over a period of 3 years. A dataset of 13524 patients was used to develop the model and another dataset of 7254 was used to validate it. The primary outcome was 30-day in-hospital mortality. Overall mortality in the development dataset was 2.31% [n = 311; 95% confidence interval: 2.06-2.56%]. Four variables were significantly associated with outcome: age, ASA class, nature of surgery (urgent/emergency vs elective), and surgical severity (major/intermediate/minor). The index with this set of variables to predict mortality in the validation sample (n = 7253) gave an AUROC = 0.9137, 85.2% sensitivity, and 81.7% specificity. This sensitivity cut-off yielded four classes of death probability: class I, <2%; class II, 2-5%; class III, 5-10%; class IV, >10%. Model application showed that, amongst patients in risk class IV, the odds of death were approximately fivefold higher (odds ratio 5.43, 95% confidence interval: 2.82-10.46) in those admitted to intensive care after a period on the regular ward than in those sent to the intensive care unit directly after surgery. The SAMPE (Anaesthesia and Perioperative Medicine Service) model accurately predicted 30-day postoperative mortality. This model allows identification of high-risk patients and could be used as a practical tool for care stratification and rational postoperative allocation of critical care resources.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Trial diagram for SAMPE model dataset analysis.
Fig 2
Fig 2. ROC curve calculated using the development SAMPE model dataset compared to the ASA model.
Fig 3
Fig 3. Model calculator developed in the Google Docs platform.
Fig 4
Fig 4. Flow of the high-risk patient’s care.
See this image and copyright information in PMC

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