Validity of pediatric index of mortality 2 scoring in a pediatric ICU setting in Ethiopia: A prospective observational study

Background: Mortality prediction scoring systems are essential tools for quality assessment and clinical decision-making in pediatric intensive care units (PICUs). The Pediatric Index of Mortality 2 (PIM2) is widely used in high-income countries, but its validity in resource-limited settings remains uncertain. Objective: To evaluate the validity of PIM2 in predicting mortality among children admitted to a PICU in Ethiopia. Methods: A prospective observational study was conducted at Hawassa University Comprehensive Specialized Hospital PICU, Ethiopia, from February 1 to July 31, 2025. All children aged 1 month to 14 years admitted during the study period were enrolled. PIM2 scores were calculated within one hour of PICU admission using physiological and clinical variables. The primary outcome was mortality at PICU discharge. Discrimination was assessed using the area under the receiver operating characteristic curve (AUROC), and calibration was evaluated using the Hosmer-Lemeshow goodness-of-fit test. Results: Of 76 enrolled patients, 31 (40.8 %) died and 45 (59.2 %) survived. Median age was 24 months (IQR 12–48 months), and 47 (61.8 %) were male. The median PIM2 score was 8.5 % (IQR 3.2–25.6 %). PIM2 demonstrated poor discrimination with an AUROC of 0.651 (95 % CI 0.525–0.777, p = 0.029). Calibration was also poor (Hosmer-Lemeshow χ²=15.8, p = 0.045). The standardized mortality ratio was 1.32, indicating observed mortality exceeded predicted mortality by 32 %. Conclusions: PIM2 showed poor performance in predicting mortality in an Ethiopian PICU setting. This finding highlights the need for local recalibration or development of context-specific mortality prediction tools for resource-limited settings with different case-mix, disease patterns, and treatment protocols.