VALIDATION OF THE PEDIATRIC INDEX OF MORTALITY 3 SCORE FOR RISK-ADJUSTED MORTALITY PREDICTION IN A TERTIARY CARE PEDIATRIC INTENSIVE CARE UNIT: A PROSPECTIVE OBSERVATIONAL STUDY

Abstract

Background: The Pediatric Index of Mortality 3 (PIM3) score is a widely used risk-adjustment tool for predicting mortality among critically ill children admitted to Pediatric Intensive Care Units (PICUs). Validation of this scoring system in different clinical settings is essential before routine implementation. Objective: To validate the PIM3 score for risk-adjusted mortality prediction in a tertiary care PICU. Methods: This prospective observational study was conducted in the PICU of a tertiary care teaching hospital. A total of 130 children aged 1 month to 18 years admitted to the PICU were enrolled. Demographic, clinical, physiological, and laboratory variables required for PIM3 score calculation were collected within the first hour of admission. The primary outcome was PICU mortality. Model performance was assessed using discrimination by area under the receiver operating characteristic curve (AUROC) and calibration using the Hosmer–Lemeshow goodness-of-fit test and standardized mortality ratio (SMR). Results: Of the 130 patients included, 20 died, resulting in an overall mortality rate of 15.4%. Mortality increased progressively across higher PIM3 risk categories, from 0% in the <1% risk group to 61.5% in the >30% risk group. The mean predicted mortality was significantly higher among non-survivors than survivors (28.7 ± 15.6% vs. 5.8 ± 4.3%; p<0.001). The PIM3 score demonstrated good discrimination with an AUROC of 0.89 (95% CI: 0.83–0.95). Calibration was satisfactory (Hosmer–Lemeshow χ²=6.21, p=0.624), with an SMR of 1.09. Conclusion: PIM3 is a reliable and valid mortality prediction model with good discrimination and calibration, making it a useful tool for risk stratification and outcome assessment in critically ill pediatric patients.