William L. Baker

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.