Have risk factors for mortality after heart transplantation changed over time? Insights from 19 years of Cardiac Transplant Research Database study

Abstract

Background: The Cardiac Transplant Research Database (CTRD) collected data from 26 U.S. institutions from January 1, 1990 to December 31, 2008 providing the opportunity for construction of a comprehensive multivariable model of risk for death after transplantation. We analyzed risk factors for death over 19 years of experience to determine how risk profiles have changed over time and how they interact with age.

Methods: A multivariable parametric hazard model for death was created for 7,015 patients entered into the CTRD. Variables collected over 19 years of experience were examined as potential risk factors and tested for interaction with date of transplantation to determine if their relative risk (RR) changed over time.

Results: The hazard for death post-transplant occurred in 2 phases: an early phase of acute risk lasting <1 year, and a late phase of relatively low, gradually increasing risk (<0.1 event/year). In the early phase, predictive models showed that ventricular assist device (VAD) at the time of transplant did not increase the RR of death for recipient transplant at 30 years of age, but the RR of death was increased by 60% (p = 0.04) at 60 years of age. Of the late-phase variables found to be risk factors, the RR of age, date of transplant and pulmonary vascular resistance changed with respect to transplant year. The overall risk of death dropped importantly over the study period, but the RR of all other variables remained unchanged. RR was 2.6 (p < 0.0001) for 25-year-old African-American (AA) versus non-AA recipients and 1.6 for 60-year-old AA recipients (p = 0.02).

Conclusion: Over 19 years, the baseline risk of death has decreased, but the specific risk factors and the magnitudes of their RR have remained unchanged. Therefore, despite advances in clinical management and improvement in overall survival, the risk profile for death after cardiac transplantation is similar to that in 1990.

Keywords: Allograft rejection; Heart Transplantation; Heart failure; Immunosuppression; Left ventricular assist device; Pulmonary hypertension; Racial disparities; Survival post-transplantation.