Adult-derived Index for Mortality Prediction After Cardiac Transplantation (IMPACT) risk score predicts short-term mortality after pediatric heart transplantation

Abstract

Background: 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.

Methods: 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.

Results: 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).

Conclusions: 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.