Impact of the United Network for Organ Sharing policy change on induction immunosuppression practice patterns and outcomes in adult heart transplant recipients

Objective: We evaluated whether the new allocation system altered induction practice patterns and affected outcomes in adult HT recipients.Design: Retrospective, observational, cohort study. Data Source: This study used data from the United Network for Organ Sharing (UNOS) database.Patients: We included adults (18+ years of age) who had undergone HT and received induction immunosuppression and were stratified based on surgery being before (January 1, 2015- May 31, 2018) and after (May 1, 2018- December 31, 2021) the UNOS allocation policy change.Measurements: Outcomes of 30 -day mortality, 1 -year mortality, and 1 -year graft failure were compared between those transplanted before and after the policy change through risk-adjusted Cox proportional hazards models while drug-treated rejection in the first year was compared using multiple logistic regression.Results: Of the 7845 HT recipients who received induction therapy, 5070 (64.6%) were transplanted before and 2775 (35.4%) after the UNOS policy change. The most used induction agents were basiliximab (56.0%) and thymoglobulin (39.3%), with thymoglobulin used more often in the new (43.1%) than old system (37.2%; p < 0.001). Among adult HT recipients who received induction, risk-adjusted hazards of 30 -day mortality (HR 0.89, 95% CI 0.67- 1.18), 1 -year mortality (HR 1.00, 95% CI 0.84- 1.19), and 1 -year graft failure (HR 0.83, 95% CI 0.60- 1.15) were similar between the old and new systems. Conversely, the adjusted odds of drug-treated rejection in the first year was lower in the new system (OR 0.52, 95% CI 0.38- 0.72).Conclusions: HT recipients in the new allocation system were more likely to receive thymoglobulin induction, which may be associated with a reduced risk of drug-treated rejection.