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Kidney donation: what are the risks?

I recently wrote a blog post "Kidney donation: why it's well worth considering".  I commented that most blog posts on this website are primarily written for fellow health professionals & others interested in an evidence-based approach to stress, health & wellbeing.  However this sequence of posts about kidney donation are different in that they are written mainly for other potential kidney donors and their friends & families.  I hope a personal story about a fellow donor's experience will be helpful, especially as my background in medicine & psychology may colour these posts usefully.

My earlier post on why donating a kidney is well worth considering underlines both the very considerable need and the very considerable benefits of kidney transplantation.  Pretty much all of us have two kidneys, why aren't we all rushing to donate one of them?  Well there are no doubt lots of reasons for this.  One big one is procrastination - so, for example, although the vast majority of people support organ donation after death, typically less than half have taken the trouble to make sure they're on an organ donation register.  It just takes a couple of minutes to sign up, for example with Organ Donation Scotland or the NHS Organ Donation site.  If you live outside the United Kingdom, it's only a quick Google search away to find out how to register as a potential organ donor after your death.  As the NHS Donation site points out "If you needed an organ transplant would you have one?  If so please help those in need of a transplant by opting to donate organs and tissue."  Do consider this seriously ... it's a painless, cost-free way of potentially relieving huge amounts of suffering. 

But what are the risks of donating an organ (in this case a kidney) while we're still alive?  The risks can usefully be divided into short term (during & around the operation) and long term (potential effects on longer term health & mortality).  The headline short term risk is the chance of being killed by the surgery.  The most widely quoted figure for this rare event is 3 deaths occurring for every 10,000 kidney transplant operations.  This estimate is derived from Segev et al's 2010 paper "Perioperative mortality and long-term survival following live kidney donation" which looked at deaths within 90 days of operation in over 80,000 patients.  More up-to-date figures are obtainable from this year's Kortram et al paper "Perioperative events and complications in minimally invasive live donor nephrectomy: a systematic review and meta-analysis" with its estimate of only 1 death in every 10,000 operations.  To quote the latter paper more fully, the authors write "One hundred ninety articles were included in the systematic review, 41 in the meta-analysis.  Conversion rate was 1.1%.  Intraoperative complication rate was 2.3%, mainly bleeding (1.5%).  Postoperative complications occurred in 7.3% of donors, including infectious complications (2.6%), of which mainly wound infection (1.6%) and bleeding (1.0%).  Reported mortality rate was 0.01%.  All minimally invasive techniques were comparable with regard to complication or conversion rate. Conclusions: The used techniques for minimally invasive live donor nephrectomy are safe and associated with low complication rates and minimal risk of mortality."   

If you want to read this more recent overview of surgical complications in full text, it's expensive to buy from the journal's website whereas you can download it freely by joining ResearchGate.  It's almost certainly the best current overview of the short term risks of kidney donation.  Many of the research studies it's based on are of only modest quality, but it's interesting to see the authors' comment "If we would adhere to our national guideline, according to which only those complications with an incidence of greater than 1% or those with severe consequences have to be disclosed to patients undergoing any surgical procedure, we would only be obliged to mention intraoperative and postoperative bleeding, conversion, wound infection (and possibly overall infectious complications), and ileus.  In addition, the possibility of a reintervention and mortality should be mentioned, regardless of their incidence.  However, is this really enough to ensure that a potential living kidney donor is optimally prepared and able to make a well-informed decision?  Rare complications like damage to other organs, or cardiovascular events may or may not necessary have “severe consequences,” so should these be mentioned or not? Also, even though many other complications are also infrequent, and may not have significant medical consequences, they may be very relevant for donors.  Prolonged pain, testicular complaints, neuropathies can be quite disconcerting to a donor who has no idea these adverse events are in fact quite “normal”."  However the bottom line (which is probably all most would-be donors want to know) is Kortram et al's statement "Based on these results, we may state that all used techniques for minimally invasive live donor nephrectomy are safe and associated with low risks of complications and an even lower risk of mortality." 

What about risks involving our longer term health and mortality?  Well again the bottom line is that long term risks are low.  Exactly how low is the subject of ongoing research and considerable debate.  So once upon a time the somewhat naive finding was bandied about that life expectancy for kidney donors was better than for non-donors, so maybe donation would improve your life expectancy!  The problem with this over-simple glance at the statistics is that researchers were "comparing apples with oranges".  Live kidney donors are typically put through extensive health screening to make sure that they're fit & well enough to donate.  This immediately means that they're not comparable to an unselected group from the general population.  It's this issue of finding an adequate control group to compare kidney donors with that has proved tricky ... and of course one needs to follow people over many years to assess any risks of long term damage from donor operations. 

I am due to donate a kidney in a few weeks' time, but it is these longer term risks that (at the moment) give me more pause for thought than the short term ones.  It's the main reason why I find the Twitter campaign "#shareyourspare" a little over-simple.  If you are a kidney donor, then I believe current research evidence shows that we are choosing a future path in life that has modestly but measurably more risk than if we hadn't decided to donate.  If we're choosing this more risky path (for many very excellent reasons), then we're foolish if we don't pay attention to the risks and take action to minimise them.  Kidney donation involves compassion for others. Intelligently facing the slightly increased life risks we then face as donors involves compassion for ourselves.  As I'll point out in a future post "Kidney donation: be an active traveller not a passive passenger", how great these risks are is primarily in our own hands.  The lifestyle choices we make will minimise or maximise the extent to which our donations are likely to shorten our own lives.  As I've said about going walking alone in the beautiful Scottish hills ... "It's possible that doing this may kill me but, if it does, I don't want it to be through my own stupidity!"

Three excellent research teams (Oslo University Hospital, Johns Hopkins Medical Institutions, and the Donor Nephrectomy Outcomes Research (DONOR) Network) have, in recent years, published papers that show increased long term risks for kidney donors.  Interestingly their more recent publications give us pause for thought whereas earlier papers from the same groups appeared to find little or no measurable risk increase.  So the Oslo group ... in their 2012 paper ... found "overall and cardiovascular mortality was lower for previous kidney donors than for matched controls", but ... in their 2014 paper ... these conclusions were reversed with concerning increases in mortality risk being reported.  Similarly work from John Hopkins ... published in 2010 ... reported no significant mortality increase, but then ... in their 2014 publication ... they found small but measurable increases in donor risk of end-stage renal disease.  A similar pattern of more cautious recent assessment of increased risk came with the DONOR Network's findings ... in their 2015 paper ... of elevated rates of pregnancy hypertension & preeclampsia.  This kind of to'ing and fro'ing as research findings are updated and improved is typical of medical progress.  The extent of increased risk has been intelligently challenged, both because many donors have "biologic and household relatedness" to those they donate to, and so may already have increased immunological & lifestyle risks compared with so-called matched controls ... and also for a variety of more involved selection & statistical reasons carefully explained in the 2016 paper "Live kidney donation: are concerns about long-term safety justified?—A methodological review" which concluded "Our detailed review of the methodology revealed key differences with respect to selection of donors and compared non-donors, data quality, follow-up duration, and statistical analysis.  In all studies, the comparison group of non-donors was healthier than the donors due to more extensive exclusion criteria for non-donors."

So what to do in the face of this uncertainty?  Well, as almost always in medicine, we call for further & better research.  And it's on its way ... see, for example, the rather sweetly named "LOng-term follow-up after liVE kidney donation (LOVE) study".  It's also worth underlining the difference between increased "relative risk" and increased "absolute risk", so the recent large-scale 2016 paper "Kidney-failure risk projection for the living kidney-donor candidate" found a several-fold increased "relative risk" for kidney donors (although the size of this risk can be challenged).  However when they reported the "absolute risk" of end-stage renal disease (ESRD) in the United States they stated "For a 40-year-old person with health characteristics that were similar to those of age-matched kidney donors, the 15-year projections of the risk of ESRD in the absence of donation varied according to race and sex; the risk was 0.24% among black men, 0.15% among black women, 0.06% among white men, and 0.04% among white women."  This means that "absolute risks" in this control population range from 24 in 10,000 to only 4 in 10,000.  So a 40-year-old white female kidney donor might increase her "absolute risk" of developing ESRD from 4 in 10,000 by a factor of 4 to a risk of 16 in 10,000.  This doesn't look so bad.  And also crucially this risk is going to be influenced by subsequent lifestyle choices ... see, for example, the blog posts "Would you like to be 14 years younger?  It's largely a matter of choice!" and "Common sense isn't common".  I'm scheduled to donate my left kidney in a few weeks' time.  I currently have concern about the operation, but not a lot.  I'm more interested in my increased long-term health risks.  I'm pleased to see that the balance of current research suggests these increased risks are modest.  And of high importance, I can personally choose to make these long-term risk increases considerably smaller by my lifestyle choices.  I plan to write further blog posts about the characteristics of donors, about the operation, about recovery, and about longer term functioning.  However when it comes to future risks, most important is likely to be the planned blog post "Kidney donation: be an active traveller not a passive passenger"! 

[Addendum February 2017 - a new review adds further interesting comment - see Janki, S., et al. (2017). "Live kidney donation: are concerns about long-term safety justified?—A methodological review" Eur J Epidemiol 32(2): 103-111.  It is available in free full text and its abstract reads: "Live kidney donors are exhaustively screened pre-donation, creating a cohort inherently healthier at baseline than the general population. In recent years, three renowned research groups reported unfavourable outcomes for live kidney donors post-donation that contradicted their previous studies. Here, we compared the study design and analysis of the most recent and previous studies to determine whether the different outcomes were due to methodological design or reflect a real potential disadvantage for living kidney donors. All six studies on long-term risk after live kidney donation were thoroughly screened for the selection of study population, controls, data quality, and statistical analysis. Our detailed review of the methodology revealed key differences with respect to selection of donors and compared non-donors, data quality, follow-up duration, and statistical analysis. In all studies, the comparison group of non-donors was healthier than the donors due to more extensive exclusion criteria for non-donors. Five of the studies used both restriction and matching to address potential confounding. Different matching strategies and statistical analyses were used in the more recent studies compared to previous studies and follow-up was longer. Recently published papers still face bias. Strong points compared to initial analyses are the extended follow-up time, large sample sizes and better analysis, hence increasing the reliability to estimate potential risks for living kidney donors on the long-term. Future studies should focus on equal selection criteria for donors and non-donors, and in the analysis, follow-up duration, matched sets, and low absolute risks among donors should be accounted for when choosing the statistical technique."

For the next post in this series, see "Kidney donation: preoperative preparation & facing challenges generally - values are central".

 

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Altruism

Thank you, James, for sharing your findings. It is a fascinating journey you are undertaking especially, for me, from the moral and philosophical standpoint. That altruism is a necessary and instinctive aspect of human survival seems self-evident to me but where are its limits? Our biological hard-wiring mostly restricts our compassion to our immediate tribe and it’s difficult for a city-dweller even to notice street beggars much less be concerned about a stranger with a failing kidney. This may be what seals our doom as a species.

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