BTS 2016: Transplantation of kidneys from small paediatric donors. Can we set a limit? Niaz Ahmad, St James's Hospital, Leeds

by Maria Dalby:  Organ donation from children aged less than 2 years is extremely rare in the UK but could offer significant scope for expanding the donor pool. Presenting data from the first UK series of kidney transplants from newborn and infant donors aged less than 2 months, Niaz Ahmad, consultant transplant surgeon at St James’s Hospital in Leeds, explained that small kidneys from neonatal donors work well in adult recipients and that the technical and surgical difficulties can be overcome.
The increase in deceased donation in recent years is mainly due to increasing numbers of older donors – paediatric donation has remained largely static over the last decade.  In 2008 the team at Mr Ahmed’s centre successfully performed an en bloc kidney transplantation from a 2-year-old who became the youngest DCD donor in the UK.¹ This prompted a review of data on paediatric donation from the NHSBT registry which showed that over a study period of 15 years (1997-2011), 47 donors aged less than 2 years were referred and 17 transplants were performed (equivalent to a utilisation rate of 65%).² Patient and graft survival rates were excellent and the investigators suggested that the scope of donation in this age group was much greater than indicated. A review of 84 infant deaths at the Great Ormond Street Hospital (GOSH) between January 2006 and October 2012 identified 45 infants (54%) as potential donors, yet none were referred for donation.³ Similarly, in Leeds, out of 18 potential donors (9% of infant deaths between 2010 and 2015) only one proceeded to transplantation.⁴ A total of 1,436 neonatal deaths were reported in the Mothers and Babies: Reducing Risk through Audits and Confidential Enquiries across the UK (MBRRACE-UK) register in 2013; applying these potential donation rates suggests that neonatal donation could increase the donor pool by between 10% (applying the Leeds rate of 9%) and 54% (applying the GOSH rate).⁴
Common arguments against kidney transplantation from small paediatric donors include concerns over small nephron mass and the risk of dysplasia, proteinuria and hyperfiltration injury. However, Mr Ahmad pointed out that the nephron numbers are finalised at 36 weeks of gestation which means babies are essentially born with adult kidneys. Dysplasia occurs in around 1 in 2,000 live births; in contrast, proteinuria is common but resolves within a year in most cases.⁵ A series of 27 kidney transplantations from donors aged between 1 and 155 days in California showed that renal function continued to evolve after transplantation, and that of 18 patients with proteinuria, only 4 remained unresolved at 6 months post-transplantation.⁵ In Leeds, Mr Ahmad and his team have performed 9 en bloc kidney transplantations from donors aged less than 2 months since 2013. Patient survival is 100%, with four of the patients having completed the first year post-transplantation and an overall median follow-up period of 286 days. One patient had primary non-function, resulting in a graft survival rate of 89%. Mr Ahmed concluded that although challenging, neonatal organ donation is feasible and well worth the additional efforts in terms of donor assessment, procurement and recipient selection.
 
References

1. Farid SG, Goldsmith PJ, Fisher J, et al. Successful outcome of paediatric en bloc kidney transplantation from the youngest donation-after-cardiac-death donor in the United Kingdom. Transpl Int 2009;22:761-2.
2. Dave RV, Hakeem AR, Dawrant MJ, et al. Renal Transplantation From Pediatric Donors in the United Kingdom. Transplantation 2015;99:1968-75.
3. Charles E, Scales A, Brierley J. The potential for neonatal organ donation in a children’s hospital. Arch Dis Child Fetal Neonatal Ed 2014;99:F225-9.
4. Wright JC, Barlow AD. The current status of neonatal organ donation in the UK. Arch Dis Child Fetal Neonatal Ed 2015;100:F6-7.
5. Perez R, Demattos A, Santhanakrishnan C, et al. Risk Factors Associated with Surgical Complications in Recipients of Kidneys from Very Small Pediatric Donors [abstract]. Am J Transplant 2013;13.