Validation of predisposition, infection, response and organ dysfunction score compared with standard severity scores in predicting hospital outcome in septic shock patients

Background. The aim of this study was to validate and compare the performance of Simplified Acute Physiology Score 3 Predisposition, Infection, Response and Organ failure (SAPS 3 PIRO) score with Acute Physiology and Chronic Health Evaluation (APACHE) II, SAPS II and SAPS 3 scores in predicting hospital outcome in septic shock patients. Methods. A prospective cohort study was conducted over a six-year period in the mixed medical-coronary care unit of a tertiary referral university teaching hospital. The performance of the severity scores was evaluated by discrimination, calibration and overall performance. Results. Eight hundred and eighty patients with septic shock were enrolled. Hospital mortality rate was 57.4%. Community-acquired infections accounted for 57.2%. The SAPS 3 PIRO showed the best discrimination with an area under the receiver operating characteristic curve (AUC) of 0.863 (95% confidence intervals, 0.838-0.889). The AUC of SAPS 3 PIRO score was statistically greater than APACHE II (0.82, P=0.001), SAPS 11 (0.819, P=0.001) and SAPS 3 (0.817, P=0.003). The calibration of all scores was poor, with the Hosmer-Lemeshow (H-L) goodness-of-fit H and C statistics <0.05. The SAPS 3 PIRO score was the best overall performance by a Brier score of 0.167. Conclusion. The SAPS 3 PIRO score provided better discrimination than the APACHE II, SAPS II and SAPS 3 but had poor calibration in our septic shock patients. SAPS 3 PIRO could be used regarding risk stratification in septic shock patients, however, this score needed to be adapted and modified with new parameters for improving the performance.