Comparison of Six-Month Post-Transplant Survival before and after Implementation of the 2018 UNOS Allocation Policy Change

Abstract

<h3>Purpose</h3> The intent of the UNOS allocation system change was to better prioritize heart transplantation (HT) for the most critically ill patients. Here, we explore six-month post-transplant survival of HT patients one year before (PRE) and after (POST) the allocation change (10/18/2018). <h3>Methods</h3> We identified all adult patients (N=3776) that underwent HT between 10/18/2017 to 10/17/2019. There were 1741 patients in the PRE group and 2035 in the POST group. Baseline clinical characteristics were compared using Mann-Whitney U test and Chi-square test as appropriate. Survival analysis was performed using Kaplan-Meier analysis and both Univariate and Multivariate Cox Proportional Hazards (PH) regression analysis adjusted for policy change, recipient age, donor age, bilirubin, creatinine, dialysis use, ischemic time, ventilator use, and ECMO use. <h3>Results</h3> There was a significant reduction in six-month survival in the POST vs. PRE group (92% vs 94%, p=0.04). On univariate analysis, the policy change was a significant predictor of mortality (HR 1.30 [1.02, 1.67]), however on multivariate analysis significance was lost (HR 1.16 [0.90, 1.50]). Median ischemic time (3.5 hrs vs. 3.0 hrs, p<0.001) and distance (234 nmi vs. 85 nmi, p<0.001) were both greater in the POST group while waitlist time (17.0 days vs. 38.0 days, p<0.001) and gender mismatch (10.9 % vs. 13.8%, p=0.007) were lower. Otherwise, there were no significant differences in baseline characteristics. Multivariate analysis also showed that pre-transplant dialysis (HR 1.85 [1.13, 3.03]), ischemic time (HR 1.13 [1.02, 1.26]), and ECMO use (HR 1.72 [1.05, 2.82]) were associated with increased mortality in the POST group. <h3>Conclusion</h3> There was a small, but significant reduction in six-month post-transplant survival following implementation of the policy change. Policy change was a significant predictor of mortality on univariate analysis, but significance was lost on multivariate analysis.