Kidney transplant candidates who are placed on a waiting list after receiving a nonrenal solid-organ transplant make up a significant and more rapidly growing cohort compared with the general kidney transplant population, researchers concluded.

Titte R. Srinivas, MD, of the Glickman Urologic and Kidney Institute at Cleveland Clinic in Ohio, and colleagues analyzed data from the national Scientific Registry of Transplant Recipients for adult renal transplant candidates placed on the solitary kidney transplant waiting list from 1995 to 2008. During this period, 280,138 patients placed on the waiting list had no previous nonrenal transplants, according to an online report in the Clinical Journal of the American Society of Nephrology. A total of 4,904 nonrenal transplant  candidates on the waiting list had previously received a nonrenal transplant, including 1,607 with a previous heart transplant, 408 with a previous lung transplant, and 2,889 with a previous liver transplant.

From 1995-1997 to 2006-2008, proportion of candidates on the waiting list for a preemptive kidney transplant who had a prior liver, heart, or lung transplant grew by 330%, 307%, and 635%, respectively. In contrast, the proportion of listings for a preemptive primary kidney transplant grew by 74% and listings for a preemptive transplant after a previous renal transplant grew by 70%.

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During the study period, 38% of nonrenal transplant candidates were listed preemptively for a renal transplant compared with 21% of other candidates.

After being placed on the waiting list, candidates who had a previous liver, heart, or lung transplant had a median survival of 6.0, 3.8, and 2.8 years, respectively, whereas candidates who had no previous transplant and those who had a previous kidney transplant had a median survival of 7.5 and 9.2 years, respectively. In adjusted analyses, nonrenal transplant candidates had a significantly increased likelihood of death compared with those who had no prior transplant. Candidates with a previous lung transplant had a 2.79 times increased death risk. Those with a previous liver or heart transplant were at 82% and 85% increased risk, respectively.

Compared with candidates who had no previous transplant, those who had a previous liver transplant were twice as likely to be listed preemptively for a renal transplant. Those who had a previous heart, lung, or kidney transplant had an 87%, 89%, and 52% increased likelihood of a preemptive listing. The likelihood of a preemptive listing was significantly greater for candidates who had a previous liver and heart transplant than for those with a previous kidney transplant.

“The clinical relevance of our findings to the transplant community and practicing nephrologists lies in the fact that nonrenal transplant kidney candidates are an emerging and growing segment of the kidney candidate pool and that appropriate transplant decision-making in this group of patients presents many complexities in the clinical and ethical domains,” Dr. Srinivas told Renal & Urology News. “The fact that kidney transplant listings are increasing in the nontransplant population is perhaps an indication of both the growing burden of chronic kidney disease in this population and the growing numbers of nonrenal transplants. This further suggests that definition of risk factors for development of ESRD and relevant preventive strategies in the nonrenal transplant population need to be studied systematically.”

The medical care of such patients, he added, may demand the structured involvement of physicians skilled in the organ-specific care of nonrenal transplant recipients, care of CKD, and ESRD planning through all phases of transplantation.