Donor Quality by UNOS Status After the 2018 Cardiac Transplantation Allocation System Change

Abstract

Introduction The allocation system for heart transplantation changed in the United States on October 18, 2018. In this analysis, we report donor quality metrics by UNOS status for patients transplanted under the new allocation system. We suspect higher quality (male, younger, less under-sized) donors will be allocated to patients with the highest acuity UNOS status recipients. Methods Adults (18 years and older) who underwent first-time heart transplantation were identified from the United Network for Organ Sharing (UNOS) registry after October 18, 2018. Donor characteristics by UNOS recipient status then were compared with one-way ANOVA and chi-squared tests, where appropriate. To determine the percent of donors that were under-sized, predicted total ventricular mass for each donors and recipient pair was calculated utilizing previously published models based on age, sex, height, and weight. Under-sizing was defined as a calculated donor mass of more than 10% under the recipient cardiac mass, based on previously reported ideal ranges. Results The analysis included 1,817 patients (Status 1: 141, Status 2: 807, Status 3: 478, Status 4: 319, Status 5: 72). Statistically significant differences were observed across the UNOS status groups, with higher acuity status recipients receiving younger donors with less donor hypertension (Table). Higher acuity status recipients were less likely to receive female donors into male recipients or to be under-sized (Status 1 & 2: 18.7% under-sized vs. Status 3, 4, & 5: 23.8% under-sized, p=0.007). Ischemic times were longer for Status 1 and 2 recipients. Donor alcohol and cocaine use were similar across UNOS statuses. Conclusions Initial analysis reveals that heart transplant recipients with the highest acuity UNOS status are receiving donor hearts with more favorable donor characteristics although with longer ischemic times. More detailed analysis of the donor characteristics and longer follow-up time will be need to further quantify and assess the impact of this measurable variation in donor quality on post-transplant outcomes.