PEDIATRIC INDEX OF MORTALITY (PIM) - A MORTALITY PREDICTION MODEL FORCHILDREN IN INTENSIVE-CARE

Objective: To develop a logistic regression model that predicts the ri sk of death for children less than 16 years of age in intensive care, using information collected at the time of admission to the unit. Desi gn: Three prospective cohort studies, from 1988 to 1995, were used to determine the variables for the final model. A fourth cohort study, fr om 1994 to 1996, collected information from consecutive admissions to all seven dedicated paediatric intensive care units in Australia and o ne in Britain. Results: 2904 patients were included in the first three parts of the study, which identified ten variables for further evalua tion. 5695 children were in the fourth part of the study (including 14 12 from the third part); a model that used eight variables was develop ed on data from four of the units and tested on data from the other fo ur units. The model fitted the test data well (deciles of risk goodnes s-of-fit test p=0.40) and discriminated well between death and surviva l (area under the receiver operating characteristic plot 0.90). The fi nal PIM model used the data from all 5695 children and also fitted wel l (p=0.37) and discriminated well (area 0.90). Conclusions: Scores tha t use the worst value of their predictor variables in the first 12-24 h should not be used to compare different units: patients mismanaged i n a bad unit will have higher scores than similar patients managed in a good unit, and the bad unit's high mortality rate will be incorrectl y attributed to its having sicker patients. PIM is a simple model that is based on only eight explanatory variables collected at the time of admission to intensive care. It is accurate enough to be used to desc ribe the risk of mortality in groups of children.