Monday, 1 November 2010

Q & A: Transplant chances

Q: I am a fifty year old man of Indian origin and have been on dialysis at the local hospital for 5 years. I am doing well but would like to have more control over my lifestyle. I am on the transplant list. My close family members have offered their kidney to me but none has been suitable because of health reasons related to the potential donors. I have been told that my chances of getting a suitable transplant are very low because of my ethnic background. I have heard that there has been a huge increase in the registration for kidney donors over the last few months. However, I am not sure how this will affect my chances. I would be most grateful for your advice.

A: Thank you for this interesting question that raises a number of important issues. I am pleased to learn that you are doing well but also fully appreciate the restrictions that hospital based haemodialysis places on such things as your diet and fluid intake, the ability to tailor the dialysis prescription to your own individual needs and of course flexibility for travel, work and family pursuits.

Home dialysis can give you far more control over the management of your kidney problems and dialysis regime than is possible in a hospital setting. The effects of transferring from hospital to home dialysis on lifestyle options, feelings of wellbeing and objective measures of kidney health can be dramatic. The patient stories speak for themselves. I see that you will have started dialysis in 2004 or 2005, around the time the National Service Framework for Renal Services was published. Standard 2 of the Framework gave individuals approaching end stage renal failure the right to receive timely preparation for renal replacement therapy so the complications and progression of their disease are minimised and their choice of clinically appropriate treatment maximised. One of the key recommendations was that patients are put onto the national transplant list within 6 months of their anticipated dialysis start date.
There are two biological barriers to successful organ transplantation. Firstly, as is the case for blood transfusion, the donor must be ABO blood group compatible with the recipient. Waiting time reflects the proportion of patients and donors with each blood group. About half of the patients on the national kidney transplant waiting list are blood group O. We know that blood group O patients wait slightly longer for a transplant than group A or AB patients but not as long as group B patients. Approximately 15% of patients on the list but only 10% of donors are blood group B so those patients wait the longest.

Secondly, it is essential to be sure that the recipient does not have antibodies directed against the donor’s HLA antigens (tissue type). If these antibodies were present at the time of transplant they would cause immediate and untreatable rejection. Someone may produce antibodies to HLA antigens if their immune cells have been exposed to another person’s tissue type that is different from their own. That can happen during pregnancy because the baby will inherit some of dad’s tissue type, following blood transfusion and previous transplantation. It will be easier to find a donor for a patient with no antibodies than for someone with antibodies and so if you have antibodies to HLA then you will wait longer for a transplant.

Having ensured that a recipient has no ABO or HLA antibodies directed against the donor the next stage of the national allocation process is to minimise the HLA (tissue type) mismatches between donor and recipient. Although HLA mismatching does not prevent successful transplantation, it is well established that HLA mismatched transplants are more likely to fail in the long term than those that are matched.

A recent study of the patients awaiting a kidney transplant in the UK between 1998 and 2005 demonstrated an imbalance between different ethnic groups in relation to their representation on the kidney transplant list, in the donor population and in the population of kidney transplant recipients. The data showed that 92% of the UK population was white, as was 77% of the kidney transplant list, 97% of the donor population and 88% of the transplants. In contrast, 6% of the UK population was Asian or black whereas they comprised 13% of the transplant list; this reflects the increased incidence of renal disease in these ethnic groups; 2% of the organ donors and 12% of the transplants were Asian or black. As mentioned above, waiting time for a transplant is influenced by ABO blood group. The average waiting time for a transplant for blood group O, A, B and AB recipients was 864, 569, 1360, 528 days respectively. Blood group B patients therefore wait by far the longest for a compatible donor. Only 10% of white patients compared with 24% of black patients and 38% of Asian patients are blood group B. As a consequence of genetic variability between individuals, there are many different tissue types. Some are more common than others and in addition there is variation between ethnic groups as to the most frequently occurring tissue types. This means that patients with rarer tissue types can wait longer for a matched donor and this is more likely to be the case when donors are predominantly from one ethnic group and the patient is from another.

Therefore the two biological factors, blood group and tissue type, underly the longer wait for a transplant experienced by Asian as compared with white patients. In the study described above. Asian patients waited on average 1849 days whereas the average wait for white patients was 1133 days. In 2003 a Task Force was set up to review the 1998 National Kidney Allocation Scheme. One aim was to help patients who had waited a very long time to receive transplants by giving them greater priority. Another aim was to resolve some of the apparent inequalities in access to transplantation resulting from biological differences whilst maintaining good transplant survival. A revised National Kidney Allocation Scheme was introduce in April 2006. The scheme prioritises patients with ideal tissue matches (000 HLA mismatches) and then assigns points to patients based on the level of tissue match between donor and recipient, the length of time spent waiting for a transplant, age of the recipient (with a progressive reduction in points given after the age of 30) and location points such that patients geographically close to the retrieval centre receive more points. The patients with the highest number of points for a particular pair of kidneys are offered these kidneys, no matter where in the UK they receive their treatment. There is careful monitoring to ensure that the scheme fulfils the objectives of improving equity of access to renal transplantation.

As a blood group O donor is also compatible with a blood group B patient, the 2006 scheme allows, under certain circumstances, a group O donor kidney to go to a group B patient so that they do not wait so long. Also, rare tissue types can now be considered matched with similar, more common tissue types so that patients with rare tissue types should not wait as long. Since the scheme was introduced the proportion of patients on the list waiting over 5 years has dropped from 17 to 8%. The average waiting time for Asian patients in the most recent analysis had fallen to 1511 days. It is important to remember that transplantation cannot occur without organ donation and a crucial aspect of improving access to transplantation is to increase the number of organ donors. Following the publication of the Organs for Transplant Report in 2008 we are working hard to increase the number of people signed up to the Organ Donor Register. A publicity campaign was launched in November 2009 that has already increased the number registered and the next phase of the campaign will be targeted at ethnic minority communities with the aim of increasing donation from those groups. Renal Patient View enables individual patients to track their status on the transplant list. NHS Blood and Transplant updates the status every day so it’s a good way for patients to keep in touch about all aspects of their kidney disease and its treatment. Renal Patient View signposts a number of high quality sites that explain issues of transplantation in more detail. I would also strongly encourage you and similar patients to discuss their individual options and concerns with regard to home dialysis, potential living donors from non family members or previously excluded family members because of blood group or tissue typing compatibility and some of the newer strategies to increase the chance of transplantation with your local kidney and transplant teams.

In summary, without knowing the details of your case, your above average wait for a transplant is probably a consequence of the biological characteristics that are used in organ allocation. The national scheme for kidney allocation is under constant review and was revised in 2006 in order to remove some of the apparent inequalities. In addition, considerable efforts are being made to increase the number of organ donors for the benefit of all those awaiting a transplant. I hope that in 2010 you have been able to tailor your dialysis to your individual needs and priorities and reconsider live donation, perhaps from ABO or HLA “incompatible” individuals or be fortunate enough to receive a call “out of the blue” asking you to come into the transplant centre for a non heart beating donor kidney transplant. Early in 2010 the campaign to increase donation was focused on Asian and black communities and if successful, this initiative should help to improve your chance of an offer.

Published in Kidney Life magazine in 2010