Utility of the IMPACT score for predicting heart transplant mortality. Analysis on a contemporary cohort of the Spanish Heart Transplant Registry.

Abstract

The Index for Mortality Prediction After Cardiac Transplantation (IMPACT) score was derived and validated as a predictor of mortality after heart transplantation (HT). The primary objective of this work is to externally validate the IMPACT score in a contemporary Spanish cohort. Spanish Heart Transplant Registry data were used to identify adult (>16 years) HT patients between January 2000 and December 2015. Retransplantation, multiorgan transplantation and patients in whom at least one of the variables required to calculate the IMPACT score was missing were excluded from the analysis (N=2810). Median value of the IMPACT score was five points (IQR: 3, 8). Overall, 1-year survival rate was 79.1%. Kaplan-Meier 1-year survival rates by IMPACT score categories (0-2, 3-5, 6-9, 10-14, ≥15) were 84.4%, 81.5%, 79.3%, 77.3%, and 58.5%, respectively (Log-Rank test: p<.001). Performance analysis showed a good calibration (Hosmer-Lemeshow chi-square for 1 year was 7.56; p=.47) and poor discrimination ability (AUC-ROC .59) of the IMPACT score as a predictive model. In a contemporary Spanish cohort, the IMPACT score failed to accurately predict the risk of death after HT.