PEDIATRIC RISK OF MORTALITY SCORING OVERESTIMATES SEVERITY OF ILLNESS IN INFANTS

Objective: To validate Pediatric Risk of Mortality (PRISM) scoring in infants and children admitted for intensive care. Design: Validation cohort. Setting: A five-bed pediatric ICU and three cots providing intensive care for surgical neonates, within a 159-bed tertiary care children's hospital. Patients: All patients admitted for intensive care during an 18-month period, January 1990 to July 1991. Methods. Admission (first 24 hrs) PRISM scoring was introduced as a routine procedure. Discretion was allowed in requesting arterial blood gas measurements and clotting studies. All other parameters were intended to be measured on all patients. Measurements and Main Results: PRISM scores were obtained on 380 (88%) of 433 patients. Median age was 15 months. A complete PRISM score was obtained in 24% of cases and a score as intended (i.e., allowing discretionary omissions) was obtained in 56% of patients. Comparison of observed and predicted mortality rates using chi square goodness-of-fit tests showed a significantly better observed outcome for all patients (chi2(5) = 12.04, p < .05). In-depth analysis indicates that the model works well for children (chi2(5) = 1.80, p > .75), but that observed outcome is significantly better than predicted for infants (chi2(5) = 17.46,p < .01). Underscoring of children is not the cause of this finding. Conclusions. In our center, PRISM scoring overestimates severity of illness in infants. PRISM scoring is not institutionally independent and therefore, at present, a comparison between units may not be justified. A reappraisal of the parameter ranges for infants is suggested.