Relationships between 2018 UNOS heart policy and transplant outcomes in metropolitan, micropolitan, and rural settings

Background: In 2018, United Network for Organ Sharing (UNOS) extended the radius for which a heart transplant candidate can match with a donor, and outcomes across population densities are unknown. We sought to determine whether the policy change was associated with differences in heart transplant waitlist time or death post-transplant for patients from rural, micropolitan, and metropolitan settings. Methods: Using the Scientific Registry of Transplant Recipients, we evaluated U.S. adult patients listed for heart transplant from Janurary 2017 to September 2019 with follow-up through March 2020. Patients were stratified by home zip-codes to either metropolitan, micropolitan, or rural settings. Fine and Gray and Cox models were respectively used to estimate Sub-distribution hazard ratios (SHR) of heart transplant with death or removal from transplant list as a competing event, and HR of death post-transplant within population densities after versus before the UNOS policy change date, October 18, 2018. Analyses were adjusted for demographics, comorbidities, and labs. Results: Among 8,747 patients listed for heart transplant, 84.7% were from metropolitan, 8.6% micropolitan, and 6.6% rural settings. The 2018 UNOS policy was associated with earlier receipt of heart transplant for metropolitan [SHR 1.56 (95% CI: 1.46-1.66)] and micropolitan [SHR 1.48 (95% CI: 1.21-1.82)] populations, but not significantly for rural [SHR 1.20 (95% CI: 0.93-1.54)]; however, the interaction between policy and densities was not significant (p = .14). Policy changes were not associated with risk of death post-transplant [metropolitan: HR 1.04 (95% CI: 0.80-1.34); micropolitan: HR 1.10 (95% CI: 0.55-2.23); rural: HR 1.04 (95% CI: 0.52-2.08); interaction p = .99]. Conclusions: The 2018 UNOS heart transplant policy was associated with earlier receipt of heart transplant and no difference in post-transplant survival within population densities. Additional follow-up is needed to determine whether improvements are sustained.