There are no differences in motivation, feelings of regret or outcomes between kidney donors who know the recipient and those who do not
'Unspecified', 'altruistic' or 'non-directed' kidney donation refers to a kidney transplant where the donor and recipient do not know each other. These donations are crucial to increasing the number of high-quality kidneys available, but ethical concerns and assumptions that they are inferior to 'specified' donations (usually from a family member or close friend) mean the practice is not widely adopted in many countries around the world.
Even in the UK, where living donation is well established and unspecified donation was legalised in 2006, only around 80-100 of the approximately 1,100 living kidney donations each year come from unspecified donors.
Researchers at the Institute of Psychiatry, Psychology & Neuroscience at King's College London and Guy's and St Thomas' NHS Foundation Trust investigated differences in the characteristics and outcomes of unspecified living kidney donors compared to specified donors.
The study, published in the September issue of American Journal of Transplantation, revealed no differences in donation rates, cost, regret or outcomes, emphasising the relative safety of unspecified kidney donation where appropriate care is provided. This is the world's largest study comparing unspecified and specified kidney donors over time.
The practice of unspecified kidney donation has been hotly debated in the transplant world for many years, mainly due to concerns about the motives and outcomes in those who choose to do it. Prior to now, there has been little data to reassure transplant professionals that this is an acceptable thing to do. My biggest hope is that the results of this study reassure members of the transplant community in the UK, and around the world, that with the appropriate support, these donations can safely proceed and help the many people waiting for a kidney transplant.
Hannah Maple, Consultant Transplant and Dialysis Access Surgeon at Guy's and St Thomas' NHS Foundation Trust and first author of the study
The researchers collected data from all 23 adult kidney transplant centres in the UK. Of the 837 potential donors, 373 went onto donate - 45 per cent of whom were unspecified donors and 55 per cent specified. Each donor completed questionnaires across four timepoints from pre-donation to one-year post-donation, as well as having their physical outcomes assessed two years after donation.
The study found that psychosocial outcomes (such as health-related quality of life, distress, self-esteem, life satisfaction and wellbeing), physical outcomes (creatinine, haemoglobin and blood pressure), or feelings of regret were no worse for unspecified compared to specified donors.
There were also no significant differences on whether they proceeded to donation, and both groups were motivated to donate by the desire to help someone.
The researchers identified several differences in the characteristics of each donor type. Unspecified donors were more likely to identify as male, have completed higher education, be blood donors, give to charity, and undertake voluntary work. Specified donors were more likely to be in a relationship, have children, and hold religious beliefs.
Most unspecified donors had become aware of living donation through stories in the media, whereas specified donors learnt about it through having a loved one with kidney failure.
The findings promote confidence in the relative safety of unspecified kidney donation.
This is the largest and most methodologically robust study of its kind, providing strong evidence that unspecified kidney donation is as safe and acceptable as specified donation. These findings challenge long-standing assumptions and highlight the potential for this approach to expand the donor pool, reduce time on transplant waiting lists, and ultimately deliver significant cost savings to the NHS, while enabling more people to receive a life-changing kidney transplant.
Professor Sam Norton, Professor of Medical Statistics and Applied Health Research, Institute of Psychiatry, Psychology & Neuroscience, and co-author of the study
Co-author Professor Joseph Chilcot, Professor of Health Psychology at the Institute of Psychiatry, Psychology & Neuroscience, added: "This study is the first of its kind and directly addresses previous concerns held by some health professionals in the transplant community."
"Our findings show that individuals who donate a kidney to someone they do not know are motivated by similar factors and experience comparable psychological and mental health outcomes compared to those who donate to a recipient they know."
"Notably, unspecified donors were more likely to engage in altruistic health behaviours, such as donating blood and registering as organ donors. These results should offer strong reassurance to the transplant community and support the continued growth of unspecified kidney donation programs, ultimately helping to save more lives."
The study was funded by the National Institute for Health and Care Research Health Service and Delivery Research programme.
More information
"Outcomes and motivations in Unspecified (non-directed altruistic) Kidney Donation: Results from a UK prospective cohort study" was published in the American Journal of Transplantation. DOI: 10.1016/j.ajt.2025.03.021.
