Referral and Evaluation for Kidney Transplantation Following Implementation of the 2014 National Kidney Allocation System

Abstract

Rationale & objective: The national kidney allocation system (KAS) implemented in December 2014 in the United States redefined the start of waiting time from the time of waitlisting to the time of kidney failure. Waitlisting has declined post-KAS, but it is unknown if this is due to transplant center practices or changes in dialysis facility referral and evaluation. The purpose of this study was to assess the impact of the 2014 KAS policy change on referral and evaluation for transplantation among a population of incident and prevalent patients with kidney failure.

Study design: Cohort study.

Setting & participants: 37,676 incident (2012-2016) patients in Georgia, North Carolina, and South Carolina identified within the US Renal Data System at 9 transplant centers and followed through December 2017. A prevalent population of 6,079 patients from the same centers receiving maintenance dialysis in 2012 but not referred for transplantation in 2012.

Exposure: KAS era (pre-KAS vs post-KAS).

Outcome: Referral for transplantation, start of transplant evaluation, and waitlisting.

Analytical approach: Multivariable time-dependent Cox models for the incident and prevalent population.

Results: Among incident patients, KAS was associated with increased referrals (adjusted HR, 1.16 [95% CI, 1.12-1.20]) and evaluation starts among those referred (adjusted HR, 1.16 [95% CI, 1.10-1.21]), decreased overall waitlisting (adjusted HR, 0.70 [95% CI, 0.65-0.76]), and lower rates of active waitlisting among those evaluated compared to the pre-KAS era (adjusted HR, 0.81 [95% CI, 0.74-0.90]). Among the prevalent population, KAS was associated with increases in overall waitlisting (adjusted HR, 1.74 [95% CI, 1.15-2.63]) and active waitlisting among those evaluated (adjusted HR, 2.01 [95% CI, 1.16-3.49]), but had no significant impact on referral or evaluation starts among those referred.

Limitations: Limited to 3 states, residual confounding.

Conclusions: In the southeastern United States, the impact of KAS on steps to transplantation was different among incident and prevalent patients with kidney failure. Dialysis facilities referred more incident patients and transplant centers evaluated more incident patients after implementation of KAS, but fewer evaluated patients were placed onto the waitlist. Changes in dialysis facility and transplant center behaviors after KAS implementation may have influenced the observed changes in access to transplantation.

Keywords: Allocation time; health care access; health care policy; kidney allocation policy (KAS); kidney failure; kidney transplantation; transplant referral; waitlisting.

Figure 1.

Inclusion/Exclusion criteria of the incident study population of patients with kidney failure, 2012–2016, with follow-up through 2017

Figure 2.

Adjusted Hazard Ratios (95% Confidence Intervals) of the Impact of the new Kidney Allocation System (KAS) policy compared to pre-KAS population on Referral, Evaluation, and Waitlisting among Incident Patients (circle) and Prevalent Patients (triangle) with kidney failure 2012–2016, with at least 12 months on dialysis (2013–2016) with follow-up through 2017 in Georgia, North Carolina, and South Carolina. Outcomes were defined as referral among all patients with ESKD; evaluation start among all patients referred, overall waitlisting among all patients who started the evaluation, and active waitlisting among all patients who started the evaluation. Models are adjusted for age, sex, race/ethnicity, cause of kidney failure, dialysis modality, BMI, comorbid conditions, informed of transplant options, insurance, pre-ESKD nephrology care, state, and neighborhood poverty.; Dialysis vintage is also included in Cox time-dependent models for evaluation start, overall waitlisting and active waitlisting.

Figure 3.

Dialysis facility-level variation in change in the proportion of patients referred from post-KAS to pre-KAS among incident patients starting dialysis 2012–2016, with follow-up through 2017, in 790 dialysis facilities in ESRD Network 6. Pre-KAS (Dec. 4, 2014), the proportion of patients referred was calculated as the number of patients referred before KAS divided by the number of patients who started dialysis prior to KAS implementation; Post-KAS, the proportion of patients referred was calculated as the number of patients referred post-KAS implementation divided by patients who were still on dialysis or who started dialysis after Dec. 4, 2014.