Adult-Derived Index for Mortality Prediction After Cardiac Transplantation (IMPACT) Risk Score Predicts Short-Term Mortality After Pediatric Heart Transplantation

Abstract

We have previously derived and validated the Index for Mortality Prediction After Cardiac Transplantation (IMPACT), which predicts short-term mortality after adult orthotopic heart transplantation (OHT). This study evaluated the predictive accuracy of the IMPACT score in pediatric OHT. The United Network for Organ Sharing registry was used to identify pediatric (< 18 years) OHT patients from 2000 to 2008. The IMPACT score was calculated for each patient. The association of IMPACT score with 1-year mortality was evaluated with univariate and multivariable logistic regression analysis. The correlation coefficient between predicted and actual 1-year mortality was determined for each IMPACT score. Kaplan-Meier survival estimates were calculated and stratified by IMPACT score. We identified 2,518 eligible pediatric OHT patients (1,128 girls [44.8%]). Mean IMPACT score was 10.3 ± 6.3 (range, 0 to 38). A total of 297 patients (11.8%) died within the first year after OHT. Each point increase in the IMPACT score increased the odds of 1-year mortality by 13% (odds ratio, 1.13; 95% confidence interval, 1.11 to 1.15; p < 0.001). The correlation coefficient between predicted and actual 1-year mortality was 0.93 (p < 0.001). One-year survival by disjoint categories of the IMPACT score was 0 to 4 (96.7%), 5 to 9 (92.9%), 10 to 14 (87.6%), 15 to 19 (81.3%), and 20 or more (64.2%; p < 0.001). In this large-cohort analysis, the IMPACT score accurately predicted mortality following pediatric OHT. The IMPACT score could therefore be useful to providers for organ allocation and prognostication in this patient population.