Abstract
This cohort study compares graft survival of kidneys from small and very small pediatric donors in women vs men with end-stage kidney disease.
Women with end-stage kidney disease have lower access to deceased-donor kidney transplants than men.1 Expanding the donor pool to include kidneys from very small pediatric donors, an underused source, may help narrow the gap in access. The objective of our study was to analyze the outcomes of our institution’s considerable experience with transplant of pediatric deceased-donor kidneys.
Methods
This cohort study was approved by the University of California, Davis, Institutional Review Board. The study was deemed exempt from informed consent as it was a retrospective review involving only information collection and analysis. We reviewed kidney transplant patients at our institution who received kidneys from deceased pediatric donors weighing less than 20 kg between February 17, 2010, and January 13, 2021. The study cohort included 327 recipients (320 adult and 7 pediatric). We compared long-term graft survival by recipient sex and donor weight (very small [1.9 to 9.4 kg] vs small [10.0 to 19.0 kg]) using a weighted log-rank test.
Results
Among a total of 327 transplant recipients (median [range] age, 51 [7-76] years, with 320 [87.9%] being aged 18-76 years), 162 (49.5%) were female, 215 patients (65.7%) received kidneys from very small donors, and 112 patients (34.3%) received kidneys from small donors. The median (range) donor age was 0.5 years (3 days to 11 years). Grafts were implanted into the iliac fossa (268 [82.0%] en bloc and 59 [18.0%] single kidney).2 Significantly more kidneys from very small donors were transplanted into female than into male patients (122 [56.7%] vs 93 [43.3%] patients; P < .001), whereas more kidneys from small donors were transplanted into male than into female patients (72 [64.3%] vs 40 [35.7%] patients; P < .001) (Table). Long-term graft survival at 9 years was excellent, with a median (range) follow-up time of 6 (0.5 to 11) years. There was no significant difference in long-term graft survival when comparing very small vs small donor groups or female vs male recipients; there was also no significant difference in long-term graft survival between female vs male recipients overall or within each donor group (Figure).
Table. Donor and Recipient Characteristics.
| Characteristics | Kidney recipient group | Total cohort (n = 327) | |
|---|---|---|---|
| Very small donor (n = 215) | Small donor (n = 112) | ||
| Recipient | |||
| Male, No. (%) | 93 (43.3) | 72 (64.3)a | 165 (50.5) |
| Female, No. (%) | 122 (56.7)a | 40 (35.7) | 162 (49.5) |
| Age, median (range), y | 51 (7-76) | 48 (11-76) | 51 (7-76) |
| Weight, median (range), kg | 62.7 (21.3-95.8) | 65.3 (31.4-96.0) | 63.8 (21.3-96.0) |
| Donor, median (range) | |||
| Age, y | 0.25 (3 d-2 y) | 2 (0.6-11) | 0.5 (3 d-11 y) |
| Weight, kg | 5.5 (1.9-9.4) | 14.0 (10.0-19.0) | 7.5 (1.9-19.0) |
| Transplant procedure type, No. (%) | |||
| En bloc | 213 (99.1) | 55 (49.1) | 268 (82.0) |
| Single kidney | 2 (0.9) | 57 (51.9) | 59 (18.0) |
P < .001.
Figure. Kaplan-Meier Graft-Survival Analysis.
Small donor weight was 10.0 to 19.0 kg; very small donor weight was 1.9 to 9.4 kg.
Discussion
To our knowledge, this cohort study is the largest published single-center series of kidney transplants from pediatric donors weighing less than 20 kg. Although there has been reluctance to transplant kidneys from these donors, it has been found that these kidneys have superior long-term graft function compared with kidneys from both living donors and standard-criteria deceased donors.3,4,5 Maluf et al found significantly lower recovery and high discard rates nationally with kidneys from very small donors weighing less than 10 kg, with only 38% of available kidneys ultimately being transplanted.5 Extrapolation from a single-center study suggested that up to 1145 paired kidneys per year could be made available nationally from these very small donors.6 This potential increase in organ availability would have an appreciable impact, given that approximately 5000 wait-listed patients die annually.
The sex disparity in access to kidney transplantation may be improving, although a gap remains.1 In our study, more female patients were matched to very small donors without significant differences in graft survival. Kidneys from smaller donors were intentionally selected for recipients with smaller body mass (generally those weighing less than 70 kg) to avoid early hyperfiltration injury. At our center, more wait-listed women than men (60.3% vs 39.7%; P < .001) met this weight criterion.
The study's limitations include its single-center design and retrospective nature. Nevertheless, this study found excellent long-term graft survival of kidneys from both small and very small pediatric donors, and there was no significant difference when comparing male vs female recipients. These results suggest that a comprehensive effort involving organ procurement organizations, transplant centers, and federal regulatory agencies may facilitate increased use of these kidneys, which may address the organ shortage and sex disparity in access to kidney transplant.
References
- 1.Melk A, Babitsch B, Borchert-Mörlins B, et al. Equally interchangeable? how sex and gender affect transplantation. Transplantation. 2019;103(6):1094-1110. doi: 10.1097/TP.0000000000002655 [DOI] [PubMed] [Google Scholar]
- 2.Troppmann C, Santhanakrishnan C, Fananapazir G, Troppmann K, Perez R. Pediatric en bloc kidney transplantation from very small (≤10 kg) donation after circulatory death (versus brain death) donors: single-center matched-pair analysis of 130 transplants. Am J Transplant. 2018;18(11):2811-2817. doi: 10.1111/ajt.14914 [DOI] [PubMed] [Google Scholar]
- 3.Winnicki E, Dharmar M, Tancredi D, Butani L. Comparable survival of en bloc versus standard donor kidney transplants in children. J Pediatr. 2016;173:169-174. doi: 10.1016/j.jpeds.2016.01.054 [DOI] [PubMed] [Google Scholar]
- 4.Sureshkumar KK, Habbach A, Tang A, Chopra B. Long-term outcomes of pediatric en bloc compared to living donor kidney transplantation: a single-center experience with 25 years follow-up. Transplantation. 2018;102(5):e245-e248. doi: 10.1097/TP.0000000000002104 [DOI] [PubMed] [Google Scholar]
- 5.Maluf DG, Carrico RJ, Rosendale JD, Perez RV, Feng S. Optimizing recovery, utilization and transplantation outcomes for kidneys from small, ≤20 kg, pediatric donors. Am J Transplant. 2013;13(10):2703-2712. doi: 10.1111/ajt.12410 [DOI] [PubMed] [Google Scholar]
- 6.Hanley H, Kim S, Willey E, Castleberry D, Mathur M. Identifying potential kidney donors among newborns undergoing circulatory determination of death. Pediatrics. 2014;133(1):e82-e87. doi: 10.1542/peds.2013-2002 [DOI] [PubMed] [Google Scholar]
