Performance of Pediatric Risk of Mortality IV in Brazilian PICUs: A Multicenter Prospective Study

This is the first Brazilian study evaluating the performance of Pediatric Risk of Mortality (PRISM) IV and the first to use the calibration belt technique.

This study aimed to evaluate the performance of PRISM IV in a large cohort of patients admitted to Brazilian PICUs.

This is a longitudinal, prospective, multicenter study conducted in 36 Brazilian PICUs with children between 29 days and 18 years old admitted from March 2020 to March 2022.

PRISM IV's performance was assessed using the standardized mortality ratio (SMR), the area under the receiver operating characteristic curve (AUROC) with 95% CI, and the calibration belt with 80% and 95% CI.

A total of 12,046 patients from 36 PICUs were included. Observed overall in-hospital mortality was higher than predicted: observed = 249 (2.1%) × predicted = 188.1 (1.56%) (SMR = 1.32 [95% CI, 1.16-1.50]); discrimination was good (AUROC = 0.86 [95% CI, 0.83-0.89]), and calibration was poor, underestimating mortality over a wide range of predicted mortality (2-61%). To explore the impact of the COVID-19 pandemic on PRISM IV's performance, we divided the study period into prevaccine and postvaccine. In the prevaccine period, the SMR was 1.38 (95% CI, 1.17-1.62), the AUROC was 0.84 (95% CI, 0.80-0.88), and the range of miscalibration was broader than in the total cohort (underestimation in the 2-98% range). In the postvaccine period, the SMR was 1.26 (95% CI, 1.03-1.51), the AUROC was 0.90 (95% CI, 0.86-0.94), and the calibration belt underestimated mortality in a narrower range of 3-46% of predicted mortality.

PRISM IV showed good discrimination but miscalibration across a wide range of predicted mortality and different COVID-19 pandemic periods in a large cohort. Further research with subgroup analyses are needed to develop strategies to improve the performance of PRISM IV in different and heterogeneous Brazilian healthcare contexts.