External validation of the Simplified Acute Physiology Score (SAPS) 3 in Spain

Abstract

Objective: To evaluate SAPS 3 performance in Spain, assessing discrimination and calibration in a multicenter study.

Design: A prospective, multicenter study was carried out.

Patients and setting: A prospective cohort study was performed in Spanish hospitals between 2006 and 2011.

Measurements and results: A total of 2171 patients were included in the study. The mean age was 61.4±16.09 years, the ICU mortality was 11.6%, and hospital mortality 16.03%. The SAPS 3 score was 46.29±14.34 points, with a probability of death for our geographical area of 18.57%, and 17.97% for the general equation. The differences between observed-to-predicted mortality were analyzed with the Hosmer-Lemeshow test, which yielded H=31.71 (p<0.05) for our geographical area and H=20.05 (p<0.05) for the general equation. SAPS 3 discrimination with regard to hospital mortality, tested using the area under the ROC curve, was 0.845 (0.821-0.869).

Conclusion: Our study shows good discrimination of the SAPS 3 system in Spain, but also inadequate calibration, with differences between predicted and observed mortality. There are more similarities with regard to the general equation than with respect to our geographical area equation, and in both cases the SAPS 3 system overestimates mortality. According to our results, Spanish ICU mortality is lower than in other hospitals included in the multicenter study that developed the SAPS 3 system, in patients with similar characteristics and severity of illness.

Keywords: Intensive care; Medicina intensiva; Probabilidad de muerte; Probability of death; Prognosis system; SAPS 3; Score; Severidad de la enfermedad; Severity of illness; Sistema pronóstico; Índice.