Written by Dr. Keren Tzukert, specialist in nephrology, Hadassah Medical Center, Ein Kerem, Jerusalem. (Translated from the Hebrew)
People suffering from advanced kidney failure need renal replacement therapy. This treatment may be given in one of three forms: hemodialysis, deceased donor kidney transplantation, or living donor kidney transplantation. The best replacement therapy is a living donor kidney transplantation.
A living donor transplantation has several advantages:
- Waiting time is significantly reduced. The waiting time for a deceased donor transplantation in Israel is 5-7 years. A living donor transplantation sometimes takes place within a few weeks or months from the time when the patient is diagnosed with kidney disease or reaches chronic kidney disease stage 5.
- A living donor transplantation is an option for a recipient who has not been on dialysis. At present only patients who have begun dialysis are eligible for a deceased donor transplantation. A living donor transplantation can be performed before or even during dialysis treatment.
Quality of the kidney:
- The donated kidney is transferred immediately to the patient’s body, with minimal ‘cold ischemia time’ (the time for which the kidney is outside the body, under refrigeration or preserved in a special solution).
- Living donors are generally healthier than deceased donors were before they died.
- If the recipient needs special treatment prior to the transplantation (such as antibody removal treatment) this can be scheduled in an organized and timely fashion. This is not possible with a deceased donor transplantation (since the timing of the procedure cannot be planned).
These advantages of a living donor kidney transplantation result in a longer survival rate for the transplanted kidney.
The physician handling a living donor transplantation is faced with an unusual dilemma – the donation can potentially harm a healthy person. This is a situation that contradicts the most basic principle of medicine: primum non nocere [‘first, do no harm’]. Actions performed with the best intentions can have undesirable results. For this reason there is widespread interest in the medical community regarding the long-term safety of living donor kidney transplantations.
The first living donor kidney transplantation was performed in 1954 by Joseph Murray, who was later awarded the Nobel Prize for Medicine. The donor and recipient were 23-year old twin brothers. The donor, Ronald Herrick, died in 2010 at the age of 79.
The most positive approach would consider this example to be ample evidence of the safety of living donor kidney transplantation, but the scientific community generally “demands” more substantial proof than a single case. Scientifically-speaking, the classic, most correct way to evaluate the safety of kidney donation is to monitor a large number of people who are identical in every medical parameter (such as age, gender, relationship to the recipient, weight, height, life style, tendency for diabetes and hypertension, etc.), and different only in that the members of one group have donated a kidney, while the members of the second group have not.
No such study has, or will ever be, carried out. Therefore, first and foremost, it is important to understand that all existing information is based on statistical analysis of data.
What data is currently available to us?
A research study conducted by Ibrahim in 2009 (New England Journal of Medicine, January 2009), which monitored more than 3,500 donors over a period of up to 40 years between 1963 and 2007, found that the survival rate for kidney donors was identical to that of the general population. The main criticism of this study was that a comparison between kidney donors and the general population is inappropriate, since kidney donors are healthier, whereas the general population includes healthy individuals as well as sick individuals whose expected life span is shorter.
A 2013 Norwegian study, headed by Mjoen, examined 1,900 living donor donations carried out over a 44-year period. Elderly people suffering from hypertension, diabetes and general poor health were excluded from the control group (in order to avoid the limitations of the previous study by comparing donors with a ‘healthier general population’ rather than a ‘general population’). In this study nine donors developed end-stage kidney failure when monitored over a period of 20 years. In other words, 0.47% themselves needed renal replacement therapy. In the control group, which numbered 42,000 people, 22 people – that is, 0.07% – developed end-stage kidney failure. Ostensibly, this is a significant difference that casts serious doubts on the safety of donating a kidney. However, much criticism has been levelled at this study. Firstly, most of the donors were first-degree relatives of the recipients, and the renal disease they developed was similar to that of the recipient. We know that renal disease in the family is a risk factor for other family members, and therefore it is not surprising that some of the donors themselves developed renal failure. Secondly, the follow up period for the donors was much longer than that of the control group. The longer a person is monitored, the more likely it is that his health will change.
A 2014 study conducted in the USA by Muzaale examined 96,217 (!) kidney donors between 1994 and 2011. The control group was much smaller – only 9,364 people. This work aroused much interest, because it observed a (seemingly) significant rise in the risk for donors. The incidence of end-stage kidney failure in the control group was 3.9 in every 10,000 people, whereas the incidence in the donor group was ten times greater – 30.8 in every 10,000 people.
How can we explain this huge difference, which was not observed in previous studies?
- The characteristics of the control group at the time of the donation were superior to those of the donor group; the members of the control group were slimmer, and there were fewer hypertension sufferers and smokers – all of which are significant risk factors in the development of kidney failure.
- The statistical manipulation used (because the control group was a tenth of the size of the donor group) skewed to a significant degree the results and their statistical validity.
The researchers themselves had reservations about the study’s results, and noted that the absolute risk of donating a kidney is very small and should be considered as such.
What conclusions can we reach on the basis of these studies?
Professionals agree that for a healthy individual donating a kidney does involve a long-term risk, but the risk is small. Should this risk preclude living donor donations?
The approach widely accepted nowadays is that the decision does not lie in the hands of the physician alone; the potential donor should be informed of the data and its limitations, so that, together, they can make an informed decision.
To summarize: We have discussed in detail only the figures that attempt (successfully???) to estimate the medical risk. It is important to note that there is considerable data indicating that the donor gains a great deal of emotional (psycho-social) benefit after his donation. By its very nature, psychological benefit is difficult to quantify, certainly relative to the ease with which we can quantify the incidence of diabetes, hypertension and kidney failure, which are easily measurable. It is even more difficult (and indeed no scientific or other attempt has been made) to assess the psycho-social harm caused to a person whose sincere offer to donate a kidney is turned down.