Performance Of Three Mortality Prediction Scores In Term Neonates

ObjectTo assess and compare the performance of pediatric risk of mortality (PRISM), pediatric index of mortality (PIM) and PIM2 in predicting mortality probability in term Chinese neonates with critical illness.MethodsA prospective study was conducted between June 1,2006 and May 31,2007 at an NICU in the Children's Hospital of Zhejiang University School of Medicine in China. A total of 243 neonates were included in the study. Information of enrolled neonates was collected within the first 24 h after admission, including age, sex, admission type, mechanical ventilation, diagnosis, length of stay, NICU outcome and all variables required to calculate the PRISM, PIM and PIM2 scores. Using the available equations of these scoring systems to calculate the probability of death. Discrimination between death and survival was assessed by the area under the receiver operating characteristic (ROC) curve. Calibration was evaluated by calculating the expected and observed number of deaths and survivors in five frequently used risk intervals. The Hosmer-Lemeshow goodness-of-fit test was employed to test the agreement between observed and expected mortality. The overall performance of score was assessed by the ratio of observed to expected number of deaths, known as the standardized mortality ratio (SMR).ResultsAmong 243 enrolled neonates in the study,36 (14.81%) neonates died in the NICU. Estimated mortality by PRISM, PIM and PIM2 were 39.33 (16.19%),35.42 (14.58%) and 27.01 (11.12%), respectively. The area under the receiver-operating characteristics (ROC) curve (95% confidence intervals, CI) were 0.834 (0.767-0.902),0.851 (0.786-0.916) and 0.854 (0.790-0.918) for PRISM, PIM and PIM2, respectively. The Hosmer-Lemeshow test gave a chi-square of 1.35 (P= 0.930) for PRISM,1.03 (P=0.960) for PIM and 4.58 (P=0.469) for PIM2. The standardized mortality rate (SMR) (95% CI) using PRISM, PIM, and PIM2 were 0.92 (0.79-1.08),1.02 (0.88-1.20) and 1.33 (1.13-1.62), respectively.ConclusionsThe three published scores (PRISM, PIM and PIM2) displayed good discrimination and calibration in the studied NICU, while PIM was considered as the most accurate and appropriate tool to predict mortality in the studied NICU.