The Kidney Not Taken: Single-Kidney Use in Deceased Donors

Abstract

Background: The nonutilization rate for kidneys recovered from deceased donors is increasing, rising to 27% in 2023. In 10% of these cases, one kidney is transplanted but the mate kidney is not. Study Design: We conducted a retrospective, single-center cohort study from December 2001 to May 2023 comparing single kidneys transplanted at our center (where the contralateral kidney was not used) to kidneys where both were transplanted separately, at least one of which was at our center. Results: We performed 395 single deceased-donor kidney transplants in which the mate kidney was not transplanted. Primary reasons for mate kidney nonutilization were: no recipient located/list exhausted (33.4%), kidney trauma/injury/anatomic abnormalities (18.7%), biopsy findings (16.7%), and poor renal function (13.7%). Mean donor and recipient ages were 51.5±14.2 and 60±12.6 years, respectively. Mean Kidney Donor Profile Index (KDPI) was 73±22%, and 104 donors (26.3%) had KDPI>85%. Mean cold ischemia was 25.6±7.4 hours, and 280 kidneys (70.7%) were imported. Compared to 2,303 concurrent control transplants performed at our center, primary nonfunction/thrombosis (5.1% single vs 2.8% control) and delayed graft function (35.4% single vs 30.1% control) were greater with single kidney utilization (both p<0.05). Median patient and death-censored graft survival were shorter in the single group (11.6 vs 13.5 years, p=0.03 and 11.6 vs 19 years, p=0.003), though the former was at least double median survival on the waiting list. In patients with functioning grafts in the single kidney group, one-year mean serum creatinine was 1.77±0.8mg/dL and eGFR was 44.8±20mL/min/1.73m 2. Conclusions: These findings suggest that many mate kidneys are being inappropriately rejected, given the acceptable outcomes that can be achieved transplanting the single kidney in appropriately selected recipients.