Pediatric risk of mortality: An assessment of its performance in a sample of 26 Italian intensive care units

Objective: To assess the validity of the Pediatric Risk of Mortality (PRISM) scoring system in accurately predicting the probability of mortality in an Italian intensive care unit (ICU) sample, Design: Prospective, observational, multicenter study. Setting: Twenty six Italian ICUs classified into two groups: a) ICUs specifically dedicated to treating pediatric patients; and b) adult ICUs treating children on a regular basis, Patients: Consecutive patients (n =1,533) < 15 yrs of age admitted during 1 yr. Interventions: None, Measurements and Main Results: To assess the performance of the PRISM scoring system, the discrimination and calibration measures were adopted both in the whole population and in 12 preselected subgroups. A good discrimination capability of the scoring system was observed for both the whole population and subgroups (areas under the receiver operating characteristic curves were never < 0.82), On the other hand, we documented an unsatisfactory calibration capability in the whole population and in most subgroups (p valves of the Hosmer-Lemeshow goodness-of fit test were < .001 in all but two subgroups). Conclusions: The analyses suggest that the unsatisfactory calibration of PRISM can be attributed to various reasons. Among those reasons, a poor performance of the system, as well as its sensitivity to factors not connected to clinical ICU performance, seem particularly important. A special caution is needed in adopting a severity of illness scoring system to assess quality of care, particularly in contexts different from the one in which the instrument was originally developed.