Comparison of Performance of the Pediatric Index of Mortality (PIM)-2 and PIM-3 Scores in the Pediatric Intensive Care Unit of a High Complexity Institution

Objective To determine the performance of each of the available pediatric index of mortality (PIM) scores, by assessing the capability for discrimination and calibration in patients admitted to a pediatric intensive care unit in Bogota. Design and setting We designed a retrospective, observational cohort study, which included all patients aged between a month and 17 years and 364 days, admitted to the pediatric intensive care unit of a high complexity university hospital between April 1, 2016 and December 31, 2018. We analyzed the standardized mortality ratio, discrimination, calibration, and net reclassification index (NRI) for each model. Results A total of 722 patients were included, the mortality rate was 3.74%, and for PIM-3, the ratio between expected and observed mortality was 0.66 [confidence interval (CI) 0.40-1.05] for PIM-2 and 1.00 (CI 0.59-1.68) for PIM-3. The Hosmer-Lemeshow (HL) test suggests inadequate calibration for PIM-2 (HL = 13.18, p = 0.11) and adequate calibration for PIM-3 (HL = 28.08, p < 0.01). The area under the diagnostic performance curves for PIM-2 and PIM-3 were 0.87 (95% CI 0.80-0.94) and 0.89 (95% CI 0.82-0.95), respectively. The NRI was -27.1%. PIM-3 classified survivors better than PIM-2, but inadequately classified nonsurvivors. Conclusion Although both models show adequate discrimination ability, PIM-3 shows a better correlation between predicted risk score and observed mortality. Thus, it may be a useful tool for measuring the internal processes of intensive care units in Colombia and for making comparisons between groups of similar characteristics. How to cite this article Quinonez-Lopez D, Patino-Hernandez D, Zuluaga CA, Garcia AA, Munoz-Velandia OM. Comparison of Performance of the Pediatric Index of Mortality (PIM)-2 and PIM-3 Scores in the Pediatric Intensive Care Unit of a High Complexity Institution. Indian J Crit Care Med 2020;24(11):1095-1102.