In the UK today, over 7,000 people are currently waiting for a kidney transplant, with only 1,600 kidney transplants performed from deceased donors annually. Until recently, the majority of donated kidneys came from people who were brain dead - individuals who had suffered brain-stem death, but whose hearts were still beating. Because treatments for head injuries have improved, and the number of serious road accidents have fallen over the last decade, there are now fewer brain-dead donors.
Consequently, the number of cardiac-death donors has increased from 3% of total donations in 2000 to 32% in 2009. A cardiac-death donor is one whose heart is not beating.
Some people have expressed concern about the quality of cardiac death donated kidneys; wondering whether they might not perform as well as those from brain-dead donors.
An Article published Online First in The Lancet, a British medical journal, concludes that both types of donated organs are as good as each other. Furthermore, cardiac-death donor kidneys, which fall outside of the UK's national allocation policy (they are distributed locally), should now be treated in the same way as kidneys from brain-dead donors.
In both cases, the kidneys acquire some degree of damage. Brain-dead patients undergo considerable hormonal and metabolic changes, while cardiac-death patient kidneys suffer warm ischemia between the heart stopping and the kidneys being flushed with cold preservation solution.
,br> In the United Kingdom, the majority cardiac-death donors are controlled donors, who have suffered massive irreversible brain injury but do not fulfill the criteria for brain-stem death. Death is certified by when the heart stops beating after a decision to withdraw life support.
Professor J Andrew Bradley, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK, and team examined the outcomes for kidneys after controlled cardiac death versus brain death, and aimed to identify factors affecting graft survival and function.
The researchers gathered information from the UK transplant registry to select a cohort of deceased kidney donors and their corresponding organ recipients, aged 18 years or more, for transplants carried out between January 1, 2000 and December 31 2007.
The study revealed the following information:
- 9,134 kidney transplant operations were performed in 23 centers.
- 8,289 kidneys were donated after brain death
- 845 kidneys were donated after controlled cardiac death.
- First-time recipients of kidneys from cardiac-death donors (n=739) or brain-death donors (n=6759) showed no difference in graft survival up to 5 years, or in kidney function (filtration rate) at 1 to 5 years after transplantation.
- For recipients of kidneys from cardiac-death donors, increasing age of donor and recipient, repeat transplantation, and cold ischaemic time of more than 12 h were associated with worse graft survival; grafts from cardiac-death donors that were poorly matched for HLA (a blood antigen) had a non-statistically significant association with inferior outcome, and delayed graft function and warm ischaemic time had no effect on outcome.
The shortage of donor organs remains one of the key challenges faced by the international transplant community. In view of our findings, cardiac-death donors represent an extremely important and overlooked source of high-quality donor kidneys for transplantation and have the potential to increase markedly the number of kidney transplants performed in the UK.
The researchers point out that allocation policy for kidneys from brain-death donors aims to make sure there is equal access to donor kidneys, regardless of the geographical location of those on the waiting list, to ensure good tissue matching for those in whom it matters most, to favour those who have waited longest, and to avoid large disparities in age between donor and recipient.
They suggest that a similar policy should be considered for kidneys from cardiac-death donors �" in other words, the findings strengthen the case for a national sharing scheme.
The authors conclude:
Kidneys from controlled cardiac-death donors provide a good outcome in terms of both graft survival and graft function in first-time recipients and should be regarded as equivalent to kidneys from brain-death donors. The factors shown to affect transplant outcome for kidneys from cardiac-death donors will help to guide clinical decision-making and inform future allocation policy.
In an accompanying Lancet Comment, Professor Sir Peter J Morris, Centre for Evidence in Transplantation, Royal College of Surgeons of England and London School of Hygiene and Tropical Medicine, London, UK, writes:
Today's report is an important contribution to the problem of increasing the supply of donor kidneys for transplantation. The results are persuasive that the use of controlled cardiac-death donors is an acceptable practice. More importantly, potential recipients of kidneys from cardiac-death donors can be reassured that their transplant outcome is not jeopardised by the source of the kidney.
"Analysis of factors that affect outcome after transplantation of kidneys donated after cardiac death in the UK: a cohort study"
Dominic M Summers, Rachel J Johnson, Joanne Allen, Susan V Fuggle, David Collett, Christopher J Watson, J Andrew Bradley The Lancet
Published Online August 19, 2010 DOI:10.1016/S0140-6736(10)60827-6
Written by Christian Nordqvist