In the JournalsPerspective

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

No difference exists in renal function between marijuana-using kidney donors and non-marijuana using donors, according to recently published findings. Researchers also found no difference in postoperative kidney function between recipient groups based on marijuana use.

“If current trends persist into the future, then there will be a further increase in both recreational and medicinal marijuana use,” David Ruckle, MD, of Loma Linda University, and colleagues wrote. “For this reason, the growing population of marijuana users will become an even more significant segment of the potential living kidney donor pool. Subsequently, consideration of marijuana using kidney donors could increase the donor pool.”

Researchers retrospectively reviewed living kidney donor transplants performed between January 2000 and May 2016. Donors were categorized into two groups based on marijuana use and termed marijuana-using donors (MUD) or non-marijuana using donors. Marijuana-using donors self-reported a history of marijuana use or tested positive for cannabinoids in a drug screening. Usage in the marijuana-using donor cohort ranged from one to 400 exposures per year, with an average of 92.

The analysis included 294 living donors and 230 of their paired recipients. Among the living donors, there were 31 marijuana-using donors and 263 non-marijuana using donors. Age, BMI, ethnicity and gender were also included in the analysis for all patients.

Researchers found no difference in donor or recipient postoperative outcomes concerning donor marijuana use, and no significant difference was found for donor demographic data including age, BMI, gender, baseline eGFR or baseline creatinine.

“This study was the first to address the effect donor marijuana use has on recipient or donor renal function postoperatively; consequently, it will open the door for future prospective multicenter studies,” the researchers wrote.

Despite the lack of effect of marijuana on kidney recipient response, the researchers concluded their study with a disclaimer about the substance.

“The results of this study should not be extrapolated to promote or support marijuana use,” they wrote. “The purpose of this study was to determine the consequences of using living kidney donors with a history of marijuana use, and if doing so would compromise either donor or recipient outcomes. Marijuana remains a mind-altering substance that can lead to psychosis, neurodegeneration, poor cognitive development and long-term cognitive deterioration even after a long period of abstinence.” – by Joe Gramigna

Disclosures: The authors report no relevant financial disclosures. Funding was provided by a grant from the Walter McPherson Society at Loma Linda University.

No difference exists in renal function between marijuana-using kidney donors and non-marijuana using donors, according to recently published findings. Researchers also found no difference in postoperative kidney function between recipient groups based on marijuana use.

“If current trends persist into the future, then there will be a further increase in both recreational and medicinal marijuana use,” David Ruckle, MD, of Loma Linda University, and colleagues wrote. “For this reason, the growing population of marijuana users will become an even more significant segment of the potential living kidney donor pool. Subsequently, consideration of marijuana using kidney donors could increase the donor pool.”

Researchers retrospectively reviewed living kidney donor transplants performed between January 2000 and May 2016. Donors were categorized into two groups based on marijuana use and termed marijuana-using donors (MUD) or non-marijuana using donors. Marijuana-using donors self-reported a history of marijuana use or tested positive for cannabinoids in a drug screening. Usage in the marijuana-using donor cohort ranged from one to 400 exposures per year, with an average of 92.

The analysis included 294 living donors and 230 of their paired recipients. Among the living donors, there were 31 marijuana-using donors and 263 non-marijuana using donors. Age, BMI, ethnicity and gender were also included in the analysis for all patients.

Researchers found no difference in donor or recipient postoperative outcomes concerning donor marijuana use, and no significant difference was found for donor demographic data including age, BMI, gender, baseline eGFR or baseline creatinine.

“This study was the first to address the effect donor marijuana use has on recipient or donor renal function postoperatively; consequently, it will open the door for future prospective multicenter studies,” the researchers wrote.

Despite the lack of effect of marijuana on kidney recipient response, the researchers concluded their study with a disclaimer about the substance.

“The results of this study should not be extrapolated to promote or support marijuana use,” they wrote. “The purpose of this study was to determine the consequences of using living kidney donors with a history of marijuana use, and if doing so would compromise either donor or recipient outcomes. Marijuana remains a mind-altering substance that can lead to psychosis, neurodegeneration, poor cognitive development and long-term cognitive deterioration even after a long period of abstinence.” – by Joe Gramigna

Disclosures: The authors report no relevant financial disclosures. Funding was provided by a grant from the Walter McPherson Society at Loma Linda University.

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    Perspective
    Benjamin E. Hippen

    Benjamin E. Hippen

    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.

    • Benjamin E. Hippen, MD, FASN, FAST
    • Nephrology News & Issues Editorial Advisory Board Member
      Clinical Professor, Department of Medicine, University of North Carolina at Chapel Hill School of Medicine
      Metrolina Nephrology Associates, P.A.
      Charlotte

    Disclosures: Hippen reports he is compensated for consulting work for Fresenius Medical Care, North America. Opinions are his own, and do not represent the opinions of Fresenius Medical Care, North America, nor Atrium Health, nor Metrolina Nephrology Associates, P.A.