121,678 patients in the United States are waiting for organ transplants. Of those patients, 100,791 are in need of a kidney. In 2014 alone, 17,107 patients received a kidney transplant, 11,570 from deceased donors, and 5,537 from living donors. Just within a single month, 3,000 patients are added to the kidney waiting list and 13 of those die while waiting for a viable organ. With the prevalence of end-stage kidney disease increasing, the need for more kidney transplants is more commanding; leaving the struggle with the disparity between supply and demand one that requires immediate attention.
Kidney Disease Improving Global Outcomes (KDIGO) guidelines suggest a psychosocial evaluation including “history of current or past substance abuse or dependence” as part of the living donor evaluation. Similarly, the American Journal of Kidney Diseases (AJKD) 2018 Core Curriculum on evaluation of living donors states that those with a history “substance abuse” are at increased risk as donors. Many institutions interpret the “substance abuse” as a history of or current use of marijuana, and thus exclude potential living donors who have used or actively use marijuana.
Over the past few years, the prevalence of marijuana use has more than doubled and may increase in the future due current legalizations for both recreational and medicinal use. David Ruckle and colleagues from Loma Linda University Health in California recently reported a study which sought to look for detrimental outcomes of kidney transplant donors and recipients, when the donor has a history of marijuana use.
As part of this study, researchers acquired data from the medical records of 658 patients, whose transplants were performed between January 2000 and May 2016, from a single institution. They studied 294 living kidney donors (31 marijuana using donors) and 230 living kidney recipients (27 marijuana using kidney recipients). Between perioperative characteristics and postoperative outcomes, there was no difference between donors and recipients based on marijuana use. There were no significant differences in long-term allograft graft function between the 2 recipient groups.
Pending further studies, these results suggest living donation with a history of marijuana use or current marijuana use may be safe for both the donor and recipient. Inclusion of these donors may lead to an important increase in the donor pool.
The narrow scope of this study limits it generalizability, though it is cautiously encouraging. As there is variability among transplant centers on definition of substance abuse, it is possible that practice can be more streamlined with more data on this topic.
Finally, the differences between cannabidiol (CBD) and tetrahdrocannabinol (THC) raise another interesting question. While both interact with CB1 receptors in the brain, the way they interact with CB2 receptors is what makes them truly different. THC forms a bond with CB1 that sends a signal to the brain, resulting in a psychoactive effect. On the other hand, CBD does not form a bond with CB1 and can even block the bond between CB1 and THC, neutralizing the effect. CBD use has also increased and may be another variable to consider in the evaluation of living donors.
If current trends persist into the future, there may be further increase in both recreational and medicinal marijuana use thus marijuana users could make up larger part of the living kidney donor pool. Though further studies are needed, it is possible that kidney donors who have used or currently use marijuana may be considered as candidates for living donation.
Kasey Belanger @BelangerKasey
PhD student at Augusta University
Take a look at this thread in ASN Communities for a discussion on this topic (ASN membership required)