DIFFERENCES IN PEDIATRIC ICU MORTALITY RISK OVER TIME

Objectives: To compare pediatric intensive care unit (ICU) mortality r isk using models from two distinct time periods; and to discuss the im plications of changing mortality risk for severity systems and quality of care assessment. Data Sources and Setting: Consecutive admissions (n = 10,833) from 16 pediatric ICUs across the United States that part icipate in the Pediatric Critical Care Study Group were recorded prosp ectively. Data collection occurred during a 12-mo period beginning in January 1993. Methods: Data collection for the development and validat ion of the original Pediatric Risk of Mortality (PRISM) score occurred from 1980 to 1985. The original PRISM coefficients were used to calcu late mortality probabilities in the current data set. Updated estimate s of mortality probabilities were calculated, using coefficients from a logistic regression analysis using the original PRISM variable set. Quality of care tests were performed using standardized mortality rati os. Results: Risk of mortality from pediatric ICU admission improved c onsiderably between the two periods. Overall, the reduction in mortali ty risk averaged 15% (p<.001). Analysis of mortality risk by age indic ated a large improvement for younger infants. The mortality risk for i nfants <1 mo improved by 39% (p<.001). Mortality risk improved by 28% (p<.001) for infants between 1 and 12 mos. Analysis of mortality risk by principal diagnosis indicated substantial improvement in respirator y diseases, including respiratory diseases developing in the perinatal period. The mortality risk for respiratory diseases improved by 45% ( p <.001). The improvement in mortality risk substantially deteriorated the calibration of the original PRISM severity system (p <.001). As a result of changing mortality risk, the standardized mortality ratios across the 16 pediatric ICUs demonstrated substantial disparities, de pending on the choice of models. Conclusions: This study documents dif ferences in pediatric ICU risk of mortality over time that are consist ent with a general improvement in the quality of pediatric intensive c are. Despite continued widespread use of the original PRISM, recent im provements in pediatric ICU quality of care have negated its usefulnes s for many intended applications, including quality of care assess men t.