Do Interventions in an ICU Affect the Predictive Ability of Pediatric Index of Mortality and Pediatric Index of Mortality-2 Scores in a Tertiary Care Hospital?

Objective: Our objective was to evaluate the effect of interventions in the initial period of stabilization (i.e., at 4 hrs) on the predictive ability of Pediatric Index of Mortality and Pediatric Index of Mortality-2 scores and to evaluate their performance in our ICU. Design: Prospective observational study. Setting: PICU of a tertiary care teaching hospital. Patients: Consecutive children aged 2 months to 17 yr admitted to our ICU from June 2010 to July 2011 were included. Interventions: None. Measurements and Main Results: We prospectively recorded the baseline characteristics, variables of Pediatric Index of Mortality and Pediatric Index of Mortality-2 at 1 and 4 hrs after admission, and the outcome data in a predesigned proforma. We compared the performance of the scores at these two time points by calculating their discriminative ability and calibration as measured by the area under curve of the receiver operating characteristic curves and the Hosmer-Lemeshow goodness-of-fit test, respectively. Of the 282 children enrolled, 93 (32.9%) died. The median (interquartile) age of the study patients was 3.5 yr (0.8, 10). The major reasons for ICU admission as well as mortality were sepsis/severe sepsis and cardiac and neurological illnesses. The area under curves for Pediatric Index of Mortality at 4 and 1 hrs were 0.73 (95% confidence interval 0.66-0.79) and 0.70 (0.63-0.77), respectively. The corresponding values for Pediatric Index of Mortality-2 were 0.72 (0.66-0.79) and 0.71 (0.64-0.78), respectively. The goodness-of-fit test showed a good calibration across deciles of risk for the two scores at both the time points (p > 0.1 for all). The calibration across different age and diagnostic subgroups was also good. Conclusion: Interventions in the first 4 hrs did not affect the predictive ability of Pediatric Index of Mortality and Pediatric Index of Mortality-2 scores. The 4-hr scores may be used in place of the 1-hr score, particularly in units where scoring is not possible with in the 1-hr time frame. (Pediatr Crit Care Med 2013; 14:e70-e76)