Reassessing Recipient Mortality Under the New Heart Allocation System: An Updated UNOS Registry Analysis

Abstract

Background: An early report of recipient heart transplantation outcomes under the new U.S. heart allocation system introduced in late 2018 found a lower post-transplant survival rate compared with that of the prior system.

Objectives: The aim of this study was to examine recipient survival under the new system by using an updated dataset.

Methods: The 2015 to 2019 United Network for Organ Sharing registry was queried for adult heart transplant recipients, stratified according to whether the subjects were listed and underwent transplant before or after October 18, 2018, when the new allocation system was implemented. The association between allocation system and recipient mortality was analyzed by using the Kaplan-Meier method and multivariable Cox proportional hazards regression.

Results: A total of 7,119 recipients met inclusion criteria: 6,004 (84%) and 1,115 (16%) listed and undergoing transplant in the old and new allocation systems, respectively. This registry update included 576 new-system recipients, more than double the amount previously analyzed. Recipients from the new system were more likely to be bridged to transplant with temporary mechanical circulatory support devices instead of durable left ventricular assist devices and had longer graft ischemic times. After adjustment, the new system was not associated with poorer survival on Kaplan-Meier survival analysis (log-rank test; p = 0.075) or multivariable Cox proportional hazards modeling (adjusted hazard ratio: 1.18; 95% confidence interval: 0.90 to 1.55).

Conclusions: The short-term survival of recipients listed and receiving a transplant under the old and new allocation systems seems to be comparable. The modification to the allocation system has resulted in several changes to the clinical profiles of patients undergoing transplants that must be closely monitored in the coming years.

Keywords: heart transplantation; mechanical circulatory support; organ allocation; recipient outcomes.

Figure 1.. Study inclusion and exclusion criteria

After application of inclusion and exclusion criteria, 7,119 heart transplant recipients and their associated donors were analyzed. A propensity-matched sensitivity analysis was performed, which included 2,158 recipients.

Figure 2.. Unadjusted Kaplan-Meier analysis of freedom from death or re-transplantation

Unadjusted Kaplan-Meier analysis of freedom from death or re-transplantation of (A) all recipients, and (B) those listed as most urgent (status 1A in old system or 1/2/3 in new system) stratified by organ allocation system. Panel (C) presents survival estimates at 90- and 180-days based upon the current report as well as the *early report by Cogswell et al. Panel (D) presents Kaplan-Meier analysis of propensity score matched cohort stratified by organ allocation system. P-values calculated using log-rank statistic.

Central Illustration.. Post-heart transplant recipient survival estimates

Post-heart transplant recipient survival estimates at 90- and 180-days under old and new US heart allocation systems based upon the current updated report as well as the *early report by Cogswell et al.