[Application of the Pediatric Index of Mortality 2 in pediatric patients with complex chronic conditions].

OBJECTIVE To evaluate the performance of the Pediatric Index of Mortality 2 (PIM2) in a pediatric intensive care unit (PICU) with a high prevalence of patients with complex chronic conditions (CCCs), and compare the performance between patients with and without CCCs. METHODS A prospective cohort study was conducted in a PICU in Brazil, with patients admitted between 2009 and 2011. The performance was evaluated through discrimination and calibration. Discrimination was assessed by calculating the area under the ROC curve, and calibration was determined using the Hosmer-Lemeshow goodness-of-fit test. RESULTS A total of 677 patients were included in the study, of which 83.9% had a CCC. Overall mortality was 9.7%, with a trend of higher mortality among patients with CCCs when compared to patients without CCCs (10.3% vs. 6.4%, p = 0.27), but with no difference in the mean probability of death estimated by PIM2 (5.9% vs. 5.6%, p = 0.5). Discrimination was considered adequate in the general population (0.840) and in patients with and without CCCs (0.826 and 0.944). Calibration was considered inadequate in the general population and in patients with CCCs (p < 0.0001 and p < 0.0001), but it was considered adequate in patients without CCCs (p = 0.527). CONCLUSIONS PIM2 showed poor performance in patients with CCCs and in the general population. This result may be secondary to differences in the characteristics between the study samples (high prevalence of patients with CCCs); the performance of the PIM2 should not be ruled out.