Marijuana use in kidney donors may have no effect on renal function in recipients

Benjamin E. Hippen, MD, FASN, FAST

This study by Ruckle et al is a welcome addition to the growing literature offering clues toward a more nuanced approach to risk assessment for living kidney donors. Addressing substance use and living kidney donors usefully illuminates a multitude of ethical considerations facing nephrologists evaluating candidates for living kidney donation, from the vantage of appropriately assessing risk to both the living donor and the recipient. While the narrow scope of this study (a single center, with a broad definition of what constitutes cannabis "use") limits the extent to which we can make generalizations about the safety to donor and recipient alike, the absence of adverse effects on both living kidney donors, and their recipients, is tentatively encouraging.

In the absence of robust evidence, clinicians (like everyone else) revert to heuristics and bias, informed (and sometimes misled) by past experiences. Rather than something to be avoided, heuristics and biases, particularly in the case of judging the risks of substance use, are worth reflecting on, and revising from time to time. In the case of cannabis (the preferred and more encompassing term, given the variety of delivery systems of cannabinoids today), it is worth noting that the genealogy of more common in-use term "marihuana" was linked by Prohibitionists in the 1930s-40s to racist propaganda, used to stoke fears of Mexican immigrants and other persons of color. The rhetoric of the “War on Drugs,” a crusade responsible for the incarceration of more people of color for non-violent legal offenses than perhaps any policy or law in recent memory, could hardly be denied a role in shaping adverse risk assessments of living kidney donors who consume cannabis. Especially when the question of short- and long-term risks of cannabis use to kidney donors and recipients otherwise approach equipoise. Ruckle and colleagues should be credited for moving our evidence base slightly off equipoise, and in favor of open-mindedness toward cannabis use in kidney donor candidates.

Absent clear evidence (or even a reasonable, testable hypothesis) regarding the harmful effects of cannabis use on kidney donors and recipients, a risk-assessment focus is better directed toward degrees and habits of cannabis use: Is there evidence of use to excess, resulting in additional risky behaviors (impaired driving) or is there evidence of impaired judgment, an undiagnosed mood disorder, or an undiagnosed chronic pain syndrome which may (if identified) have long-term consequences for a donor candidate? As Ruckle et al note in their discussion, it is useful, for the purpose of risk-assessment, to distinguish categories of cannabis consumption (e.g. synthetic cannabinoids, long-term smoke inhalation and CV risks, etc.) The point is not to *assume* that cannabis use is inexorably indicative of another clinically pertinent disorder, but rather to treat it as merely a checkpoint for the transplant nephrologist to explore and differentiate further.

Reference:

Grimm B. “The Racist ‘Strain’ of Marijuana” available at https://splinternews.com/the-racist-strain-of-marijuana-1822511845 . Last accessed 11/19/18.