Longer Pretransplantation Dialysis Exposure Associated with Increased Failure Risk

There are few definitive data on the impact of dialysis exposure prior to nonpreemptive living donor kidney transplantation on allograft outcomes. According to John S. Gill, MD, MS, and colleagues, the mechanisms that underlie the previous findings of the detrimental association of dialysis exposure with transplant failure remain uncertain and may differ between living and deceased donor transplant recipients.

In light of recent changes to the policy on allocation of deceased donor kidneys in the United States, nonpreemptive patients on the transplant wait list may be backdated to the date of initiation of dialysis. This change in policy may increase equity in access to deceased donor transplantation, but also may reduce the impetus for early referral of patients who have initiated dialysis.

Dr. Gill et al. conducted an analysis designed to identify the association between the duration of dialysis exposure prior to nonpreemptive living donor transplantation and allograft outcomes; the researchers also sought to identify factors that affect the duration of pretransplant dialysis exposure, including an evaluation of the variation between transplantation centers. Results of the analysis were reported in the American Journal of Kidney Diseases [2018;71(5):636-647].

The researchers analyzed data from the Scientific Registry of Transplant Recipients; the registry includes information on deceased donors, wait-list candidates, and transplant recipients in the United States, submitted by members of the Organ Procurement and Transplantation Network. The study population included adults ≥18 years of age who underwent first kidney transplant from January 1, 2000, through November 30, 2016. Following application of exclusion criteria, the final study cohort included 77,607 patients. The outcomes of interest were kidney transplant failure from any cause including death, death-censored transplant failure, and death with allograft function.

The study defined dialysis exposure prior to living donor transplantation as the difference between the date of the first maintenance dialysis treatment and the date of the living donor transplantation; preemptive transplant recipients were assigned a value of zero.

Of the 77,607 study patients, 26,217 (34%) were preemptive transplant recipients. Of the 51,390 nonpreemptive recipients, median duration of dialysis exposure was 14 months. The proportion of preemptive transplant recipients per year increased from 32% to 40% (P<.001) during the study period. The duration of dialysis exposure among nonpreemptive transplant recipients increased from a median of 13 months in 2000 to 15 months in 2016 (P<.01).

Median follow-up was 6.8 years. During that time, 26% (n=20,347) had transplant failure from any cause including death. Of the patients with transplant failure, 50% (n=10,138) returned to dialysis therapy or underwent repeat preemptive transplantation and 50% (n=10,209) died with a functioning transplant.

Preemptive transplant recipients had the highest overall survival; patients with longer pretransplantation dialysis exposure had higher transplant failure. Following adjustment for differences in known risk factors for transplant failure, in comparisons with the reference group of patients with 0.1 to 3.0 months of pretransplantation dialysis exposure, the risk for transplant failure was lower among preemptive transplant recipients, while the risk for transplant failure was increased for patients with dialysis exposure >6 months. The risk was generally increased in patients with longer pretransplantation dialysis exposure.

There was a marked difference among centers in length of pretransplantation dialysis exposure: median of 11.0 months versus 19.0 months in centers in the 10th and 90th percentiles of dialysis exposure, respectively. Allowing for recipient variables, there was nearly a 2-fold variation in time to living donor transplantation between the fastest and the slowest centers. For example, the median duration of pretransplantation dialysis exposure among black recipients varied 1.97-fold (13.8 to 27.2 months). Allowing for center-level variables, median times to nonpreemptive living donor transplantation were shorter in centers within the highest proportion of living donor transplant recipients and proportion of preemptive transplantations. In addition, between the fastest and the slowest centers, there was a 2-fold variation in the duration of pretransplantation dialysis exposure.

The researchers cited the inability to determine why dialysis exposure is associated with an increased risk for transplant failure as a limitation to the study.

“In summary, the duration of pretransplantation dialysis exposure in nonpreemptive living donor transplant recipients is highly variable between centers and associated with increased risk for transplant failure. Sociodemographic factors are associated with longer times to nonpreemptive living donor transplantation, but some centers are able to deliver timely access to living donor transplantation despite these challenges. Strategies to increase the efficiency of living donor transplantation in nonpreemptive recipients are warranted,” the researchers said.

Takeaway Points

  1. Researchers conducted a retrospective cohort study to examine the impact of dialysis exposure prior to nonpreemptive living donor kidney transplantation on allograft outcomes.
  2. Outcomes of interest were kidney transplant failure from any cause, including death, death-censored transplant failure, and death with allograft function.
  3. There was an association between longer pretransplantation dialysis exposure and increased risk for allograft failure.