The national landscape of deceased donor kidney transplantation for the highly sensitized: Transplant rates, waitlist mortality, and posttransplant survival under KAS

Abstract

Deceased donor kidney transplantation (DDKT) rates for highly sensitized (HS) candidates increased early after implementation of the Kidney Allocation System (KAS) in 2014. However, this may represent a bolus effect, and a granular investigation of the current state of DDKT for HS candidates remains lacking. We studied 270 722 DDKT candidates from the SRTR from 12/4/2011 to 12/3/2014 ("pre-KAS") and 12/4/2014 to 12/3/2017 ("post-KAS"), analyzing DDKT rates for HS candidates using adjusted negative binomial regression. Post-KAS, candidates with the highest levels of sensitization had an increased DDKT rate compared with pre-KAS (cPRA 98% adjusted incidence rate ratio [aIRR]:_1.27 1.77_2.46 P = .001, cPRA 99% aIRR:_3.18 4.36_5.98 P < .001, cPRA 99.5-99.9% aIRR:_16.91 24.29_34.89 P < .001, and cPRA 99.9%+ aIRR:_8.79 11.58_15.26 P < .001). To determine whether these changes produced more equitable access to DDKT, we compared DDKT rates of HS to non-HS candidates (cPRA 0-79%). Post-KAS, cPRA, 98% candidates had an equivalent DDKT rate (aIRR:_0.65 0.94_1.36 , P = .8) to non-HS candidates, whereas 99% candidates had a higher DDKT rate (aIRR:_1.19 1.68_2.38 , P = .02). Although cPRA 99.5-99.9% candidates had an increased DDKT rate (aIRR:_2.46 3.50_4.98 , P < .001) compared to non-HS candidates, cPRA 99.9%+ candidates had a significantly lower DDKT rate (aIRR:_0.29 0.40_0.56 , P < .001). KAS has improved access to DDKT for HS candidates, although substantial imbalance exists between cPRA 99.5-99.9% and 99.9%+ candidates.

Keywords: clinical research/practice; health services and outcomes research; kidney transplantation/nephrology; organ allocation; organ procurement and allocation; panel-reactive antibody (PRA); sensitization.

Figure 1.

Monthly prevalence of highly sensitized candidates on the waitlist during the study period. Post-KAS, cPRA 99.9%+ candidates represent the most common group of highly sensitized candidates on the waitlist. After an initial increase in the prevalence of highly sensitized candidates immediately after KAS, these candidates now represent a smaller proportion of the waitlist. cPRA, calculated panel reactive antibody; D, December; M, March; J, June; S, September

Figure 2.

Relative DDKT^# Rates for Different cPRA* Groups Post-KAS Compared to Pre-KAS KAS has produced sustained changes to DDKT rates for most cPRA categories. Three years post-KAS, cPRA 99.9%+, 99.5-99.9%, 99%, and 98% candidates have increased DDKT rates compared to pre-KAS. Conversely, cPRA 80-89% candidates have lower DDKT rates post-KAS compared to pre-KAS. ^#DDKT, deceased donor kidney transplantation; *cPRA, calculated panel reactive antibody Grey horizontal line represents an incidence rate ratio of 1, which would represent equivalent DDKT rates post-KAS compared to pre-KAS

Figure 3.

Relative DDKT^# Rates for Different cPRA* Groups Compared to cPRA 0-79 DDKT rates become more balanced across cPRA groups post-KAS. However, cPRA 99.5-99.9% are transplanted at a substantially higher rate than 0-79% candidates post-KAS, whereas cPRA 99.9%+ candidates are transplanted at a lower rate. ^#DDKT, deceased donor kidney transplantation; *cPRA, calculated panel reactive antibody Grey horizontal line represents an incidence rate ratio of 1, which would represent equivalent DDKT rates between a given cPRA category and cPRA 0-79%.

Figure 4.

Cumulative incidence of DDKT^# for different cPRA* groups pre-KAS and post-KAS. The cumulative incidence of DDKT becomes more similar between cPRA groups following KAS compared to before KAS. Pre-KAS and Post-KAS, cPRA 99.9%+ candidates have the lowest cumulative incidence of DDKT. ^#DDKT, deceased donor kidney transplantation; *cPRA, calculated panel reactive antibody Cumulative incidence of DDKT estimated under a competing risks framework, accounting for a candidate’s competing risk of death or removal from the waitlist due to deteriorating medical condition

Figure 5.

Cumulative incidence of waitlist mortality for different cPRA* groups pre-KAS and post-KAS. The cumulative incidence of waitlist remains similar between cPRA groups post-KAS and pre-KAS. *cPRA, calculated panel reactive antibody Cumulative incidence of waitlist mortality estimated under a competing risks framework, accounting for a candidate’s competing risk of deceased donor kidney transplantation