Comparação entre dois escores de prognóstico (PRISM e PIM) em unidade de terapia intensiva pediátrica Comparison of two prognostic scores (PRISM and PIM) at a pediatric intensive care unit

OBJETIVO: Comparar o desempenho do PRISM (Pediatric Risk of Mortality) e o PIM (Pediatric Index of Mortality) em uma unidade de terapia intensiva pediátrica geral investigando a relação existente entre a mortalidade e a sobrevivência observadas com a mortalidade e sobrevivência estimadas pelos dois escores. MÉTODOS: Estudo de coorte contemporâneo realizado entre 1° de junho de 1999 a 31 de maio de 2000 na unidade de terapia intensiva pediátrica do Hospital São Lucas da Pontifícia Universidade Católica do Rio Grande do Sul. Os critérios de inclusão no estudo e o cálculo do PRISM e do PIM foram feitos conforme preconizado e utilizando as fórmulas de seus artigos originais. Para estatística, utilizou-se o teste z de Flora, teste de ajuste de Hosmer-Lemeshow, área sob a curva típica de um recebedor operador de características (curva ROC) e teste de correlação de Spearman. O estudo foi aprovado pelo Comitê da instituição. RESULTADOS: Internaram na unidade de terapia intensiva pediátrica 498 pacientes, sendo 77 excluídos. Dos 421 pacientes estudados, 33 (7,83%) foram a óbito. A mortalidade estimada pelo PRISM foi de 30,84 (7,22%), com standardized mortality rate 1,07 (0,74-1,50), z = -0,45. Pelo PIM, foi de 26,13 (6,21%), com standardized mortality rate 1,26 (0,87-1,77), z = -1,14. O teste de ajuste de Hosmer-Lemeshow obteve um qui-quadrado 9,23 (p = 0,100) para o PRISM e 27,986 (p OBJECTIVE: To compare the performance of the PRISM (Pediatric Risk of Mortality) and the PIM (Pediatric Index of Mortality) scores at a general pediatric intensive care unit, investigating the relation between observed mortality and survival and predicted mortality and survival. METHODS: A contemporary cohort study undertaken between 1 June 1999 and 31 May 2000 at the Pontifícia Universidade Católica do Rio Grande do Sul, Hospital São Lucas pediatric intensive care unit. The inclusion criteria and the PRISM and PIM calculations were performed as set out in the original articles and using the formulae as published. Statistical analysis for model evaluation employed the Flora z test, Hosmer-Lemeshow goodness-of-fit test, ROC curve (receiver operating characteristic) and Spearman's correlation tests. The study was approved by the institution's Ethics Committee RESULTS: Four hundred and ninety-eight patients were admitted to the pediatric intensive care unit, 77 of whom presented exclusion criteria. Thirty-three (7.83%) of the 421 patients studied died and 388 patients were discharged. Estimated mortality by PRISM was 30.84 (7.22%) with a standardized mortality rate of 1.07 (0.74-1.50), z = -0.45 and by PIM this was 26.13 (6.21%) with a standardized mortality rate of 1.26 (0.87-1.77), z = -1.14. The Hosmer-Lemeshow test gave a chi-square of 9.23 (p = 0.100) for PRISM and 27.986 (p < 0.001) for PIM. The area under the ROC curve was 0.870 (0.810-0.930) for PRISM and 0.845 (0.769-0.920) for PIM. The Spearman test returned r = 0.65 (p < 0.001). CONCLUSION: Analyzing the tests we can observe that, although the PIM test was less well calibrated overall, both PRISM and PIM offer a good capacity for discriminating between survivors and moribund patients. They are tools with comparable performance at the prognostic evaluation of the pediatric patients admitted to our unit