Validation of Pediatric Index of Mortality 3 in a Single Referral Pediatric Intensive Care Unit in Iran

Objectives: The research aimed to evaluate the Pediatric Index of Mortality 3 (PIM-3) for determining the risk of mortality among pediatric intensive care unit patients. Methods: A retrospective analysis was conducted on case records, as well as patient data from all admissions to the PICU of Mofid Children’s Hospital, Tehran, from October 2017 to February 2018. Employing an android calculator application, the PIM-3 score was estimated early within the first PICU admission. Then, the PIM-3 score and mortality rate were analyzed using the Mann-Whitney U test. In addition, calibration and discrimination were assessed by the Hosmer-Lemeshow goodness-of-fit test and a receiver operating characteristic curve method, respectively. Finally, the Standardized Mortality Ratio (SMR) was calculated. Results: In this study, 365 young infants, ranging from 10 to 29-months-old, were included. The overall mortality rate was 10.4%. Further, the patients’ PIM-3 scores ranged from 0.06% to 2.37% (95% confidence interval), with a mean of 1.45% (4.16% in non-survivors and 1.14% in survivors). The SMR was estimated at 7.18, demonstrating the underprediction of the death rate. The AUC of 0.714 (95% CI: 0.626 to 0.801) demonstrated a fair to good discrimination power of PIM-3 as an international standard risk-adjusted mortality indicator. Moreover, this score underpredicted the risk of mortality in young infants admitted to our ICU in 2017. Generally, the prediction was weak among low-risk patients. Therefore, the Pediatric Index of Mortality-3 score has the potential to be implemented in our PICU by modifying the expected probability of death by multiplying the original PIM-3 score by 7.12.