Development and Validation of a Pediatric Comorbidity Index.

Comorbidity scores are widely used to help address confounding bias in nonrandomized studies conducted within healthcare databases, but existing scores were developed to predict all-cause mortality in adults and may not be appropriate for use in pediatric studies. We developed and validated a pediatric comorbidity index, using healthcare utilization data from the tenth revision of the International Classification of Diseases. Within the MarketScan database, pediatric patients (<18 years) continuously enrolled between October 1, 2015-September 30, 2017 were identified. Logistic regression was used to predict the 1-year risk of hospitalization based on 27 predefined conditions and empirically-identified conditions derived from the most prevalent diagnoses among patients with the outcome. A single numerical index was created by assigning weights to each condition based on its beta coefficient. We conducted internal validation of the index and compared its performance to existing adult scores. The pediatric comorbidity index consisted of 24 conditions and achieved a c-statistic of 0.718 (95% confidence interval [CI] 0.714, 0.723). The index oasutperformed existing adult scores in a pediatric population (c-statistics ranging from 0.522 to 0.640). The pediatric comorbidity index provides a summary measure of disease burden and can be used for risk adjustment in epidemiologic studies of pediatric patients.