Two recent studies,, one from Norway and another from the U.S., confirm that living kidney donors have a higher long-term risk of end-stage renal disease than their healthy matched cohorts. This has resulted in massive editorials to journals about the “limitations” of the studies, or simple minimization of the results (eg. Sure, LKDs have and 8-11X increased risk for ESRD, but the *overall* risk is still low, so no worries). On the surface, this seems like standard academic poking, but one recent example demonstrates that it is not.
The issue these three authors take with the U.S. study is in how it concocted its matched cohort. In short, the original authors didn’t use one healthy two-kidneyed person for every one living kidney donor. They used approximately 1 control for every 10 LKDs. This is known as bootstrapping. And our three authors here disapprove of the practice.
But you know who else bootstrapped their control group? Segev back in 2010 when he declared that living kidney donors aren’t dropping dead any faster than non-donors after a median 6.3 years. Did anyone criticize him for that?
Nope. In fact, transplant centers held up that study as “proof” that living donation was safe. Some even posted it on their website.
Conclusion: Bootstrapping is bad when it proves that living kidney donors’ health is at risk. When it doesn’t; then it’s perfectly acceptable.
**PS. Segev used a “woefully inadequate” and “useless for analysis or research” database for his LKDs too. But no one seemed to mind that either.
Allegretti AS, Yeung MY, & Riella LV (2014). Counseling Potential Donors to the Risk of ESRD After Kidney Donation: Glass Half-Full or Half-Empty? American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons PMID: 25167951