Characteristics and Performance of Unilateral Kidney Transplants from Deceased Donors

Abstract

Background and objectives: The fraction of kidneys procured for transplant that are discarded is rising in the United States. Identifying donors from whom only one kidney was discarded allows us to control for donor traits and better assess reasons for organ discard.

Design, setting, participants, & measurements: We conducted a retrospective cohort study using United Network for Organ Sharing Standard Transplant Analysis and Research file data to identify deceased donors from whom two kidneys were procured and at least one was transplanted. Unilateral pairs were defined as kidney pairs from a single donor from whom one kidney was discarded ("unilateral discard") but the other was transplanted ("unilateral transplant"). Organ quality was estimated using the Kidney Donor Risk Index and Kidney Donor Profile Index (KDPI). We compared all-cause graft failure rates for unilateral transplants to those for bilateral transplant Kaplan-Meier methods, and life table methodology was used to evaluate 1-, 2-, 3-, and 5-year survival rates of transplants from bilateral and unilateral donors.

Results: Compared with bilateral donors (i.e., both kidneys transplanted) (n=80,584), unilateral donors (i.e., only one kidney transplanted) (n=7625) had higher mean terminal creatinine (1.3±2.1 mg/dl versus 1.1±0.9 mg/dl) and KDPI (67%±25% versus 42%±27%), were older, and were more likely to have hypertension, diabetes, hepatitis C, terminal stroke, or meet Centers for Disease Control and Prevention high-risk donor criteria. Unilateral discards were primarily attributed to factors expected to be similar in both kidneys from a donor: biopsy findings (22%), no interested recipient (13%), and donor history (7%). Anatomic abnormalities (14%), organ damage (11%), and extended ischemia (6%) accounted for about 30% of discards, but were the commonest reasons among low KDPI kidneys. Among kidneys with KDPI≥60%, there was an incremental difference in allograft survival over time (for unilateral versus bilateral transplants, 1-year survival: 83% versus 87%; 3-year survival: 69% versus 73%; 5-year survival: 51% versus 58%).

Conclusions: A large number of discarded kidneys were procured from donors whose contralateral kidneys were transplanted with good post-transplant outcomes.

Keywords: Allografts; Biopsy; Centers for Disease Control and Prevention (U.S.); Death; Hepatitis C; Life Tables; Retrospective Studies; Stroke; Survival Rate; Tissue Donors; United States; cadaver organ transplantation; clinical epidemiology; creatinine; diabetes mellitus; hypertension; kidney; kidney transplantation; transplant outcomes.

Figure 1.

Flow chart of the cohort study population. Of 212,926 deceased donor kidneys recovered for transplantation from 2000–2015, 176,418 were from the 88,209 donors who had two kidneys procured and had relevant data available. Of these, 7625 were from “unilateral donors” from whom only one procured kidney was transplanted, and the remaining 161,168 were from “bilateral donors” from whom both kidneys were separately transplanted. BMI, body mass index; EKI, double/en-bloc kidney; KDRI, Kidney Donor Risk Index.

Figure 2.

Distribution of unilaterally discarded kidneys by discard category and KDRI (n=7625 kidneys), 2000–2015. Organ damage and anatomical abnormalities were the most frequent reasons for discard among low-KDRI (i.e., high quality) kideys, but accounted for a decreasing fraction of discards as KDRI increased. Biopsy findings, poor function, and inability to locate a recipient accounted for an increasing fraction of discards as KDRI increased. IQR, interquartile range; KDRI, Kidney Donor Risk Index.

Figure 3.

Organ quality (KDPI) of unilaterally discarded, deceased donor kidneys stratified by discard type (n=7625 kidneys), 2000–2015. The number of unilateral discards rose with increasing KDPI (i.e., with worsening kidney quality), with biopsy findings emerging as the dominant reason for discards as KDPI increased. KDPI, Kidney Donor Profile Index.