Combined Thoracic-Kidney Transplantation Practices May Exacerbate Existing Geographic Disparities in Access to Deceased Donor Kidney Transplantation

Abstract

The rate of combined thoracic-kidney transplantation (CTKT) continues to increase. Our allocation system affords these candidates priority over those listed for kidney alone, yet, there are no standard listing criteria for CTKT and practices may vary by center. It is not understood how CTKT impacts access to deceased donor kidney transplantation (DDKT). Here we examine state-level CTKT practices in relation to end stage renal disease (ESRD) burden. This retrospective study identified all patients that received DDKT and the subset of CTKT (heart or lung and DDKT) in 2014-2019 using the Scientific Registry of Transplant Recipients. Recipients were categorized by permanent state of residence at transplant and were excluded if residence was unknown or outside the U.S. Using the U.S. Renal Data System, ESRD burden was defined as 2014 period prevalence of ESRD among adult, transplant-eligible patients per million population (PMP) by state. Eligibility was determined using our institution's standard criteria. Spearman's correlation was used to evaluate state CTKT and DDKT counts. CTKT proportion was compared to ESRD Burden. 70372 DDKT were included, of which 810 were CTKT. CTKT and DDKT counts by state (Figure 1A-B) were highly correlated (r=0.89, p<0.001). However, state-level percent DDKT used for CTKT ranged from 0-2.8% (median 1, IQR 0.62, 1.39). States in the top quartile of CTKT proportion (red bars, Figure 1C) accounted for 51% of all CTKT (412/810). Moreover, 62% of these high CTKT proportion states (8/13) had an ESRD burden lower than the U.S. median (1503 PMP, IQR 974, 1783; Figure1D). These data demonstrate wide variability in proportion of CTKT by state despite correlation of CTKT and DDKT counts. States with high CTKT proportion and low ESRD burden may reflect more liberal listing practices. Our results suggest CTKT practices may exacerbate existing geographic disparities in access to DDKT.