Exploring the impact of substance use on liver transplantation
High Stakes: Navigating the Hazy Intersection of Marijuana and Liver Transplants
BY JOVEN TRISTEZA, MD, THOMAS RULI, MD, AND MOHAMED SHOREIBAH, MD
Marijuana is currently illegal at the federal level and is listed as a schedule I substance. However, marijuana for medical and recreational use has been legalized by several states, leading to an increase in its use. This unclear and disparate status of marijuana has created a smoky situation for patients being evaluated for liver transplant. Multiple studies have shown marijuana to provide medical benefits, while other studies in liver transplant patients have shown that it does not affect posttransplant outcomes. Those studies have helped inform decision-making for liver transplant selection committees across the country, where marijuana use is evaluated in the context of the patient’s medical and social history, as well as the history of other substance use. Though we do not encourage its use, we do not believe that marijuana use should be the singular reason to deny a patient listing for liver transplant.
Marijuana has been studied extensively regarding its effects on the human body. The main compounds in marijuana are tetrahydrocannabinol, or THC, and cannabidiol, or CBD. These compounds exhibit many effects that we observe clinically through the endocannabinoid system. Beneficial effects related to the gastrointestinal tract include relief from nausea and vomiting and stimulation of appetite in patients with anorexia. Other benefits outside the GI tract include alleviation of chronic pain and management of some forms of drug-resistant epilepsy. Ongoing studies are investigating the role of marijuana in other medical conditions.1,2 At least equally notable are marijuana’s potential adverse effects, which include tachycardia, hypertension, agitation, nausea, psychosis, and hallucinations.2 Marijuana may also increase the risk of heart failure, acute myocardial infarction, and stroke.3
The exact effect of marijuana on the liver remains inconclusive. Receptors for endocannabinoids have been associated with steatosis and fibrosis in some studies. However, some evidence also suggests that marijuana may reduce inflammation in the liver.2 Small, prospective studies have not been able to link marijuana use with hepatic laboratory abnormalities, and there is currently no significant association between marijuana and liver disease, injury, or cirrhosis. Of particular relevance to liver transplant recipients is marijuana’s effect on cytochrome P450 enzyme function, especially CYP3A4 which is the CYP class that metabolizes tacrolimus, a common immunosuppressant used in liver transplant patients. Marijuana inhibits CYP3A4 which could increase tacrolimus levels, potentially leading to morbidity. One strategy to mitigate this process is closer monitoring of tacrolimus levels for patients using marijuana.
The once-presumed increased risk of fungal infection — particularly Aspergillus — for liver transplant patients who use marijuana has been refuted. Furthermore, there have been concerns by liver transplant selection committees that marijuana use may be related to a greater risk of post–liver transplant noncompliance, infections, or even death. However, marijuana use on its own has not been associated with these concerns in the liver transplant population.4
The practice of excluding marijuana users from being listed for liver transplant does not appear to be evidence based. In a 2018 study focusing on US transplant centers, 40% of centers would not accept any marijuana use, and only 28% would list those who were taking medical marijuana for transplant. Interestingly, eight states have passed legislation prohibiting withholding transplant evaluation for marijuana users if it is solely based on their marijuana use.5 In the 5 years since that study was published, there have been major changes in the legality of marijuana. A future study of interest could assess how these changes have affected the position of transplant centers.
The sociopolitical and transplant medicine worlds alike continue to adapt to the legalization of marijuana. While marijuana use is associated with adverse effects, its potential for benefit for a variety of medical conditions is an evolving area that has shown promise. It is therefore logical to view marijuana as a pharmacologic agent with potential for risks and benefits, but not necessarily a sole reason to exclude patients from listing for liver transplant. The current data are reassuring in that those who use marijuana and receive liver transplantation are not at higher risk of posttransplant complications, infections, or death when compared to those who do not use it. Should marijuana use exist in the context of substance use disorder or other behavioral and mental health issues, then the case warrants careful multidisciplinary evaluation prior to consideration for liver transplant. The aim of our discourse is not to encourage the use of marijuana in patients being considered for liver transplant but rather to discourage their exclusion from listing solely on the basis of marijuana use. In the pursuit of an equitable organ allocation system, our hope is that this work facilitates a more informed discussion and a change in policy in liver transplant programs that may still consider marijuana use an exclusion criterion.
Joven Tristeza, MD, and Thomas Ruli, MD, are residents in internal medicine at the University of Alabama at Birmingham; Mohamed Shoreibah, MD, is a specialist in gastroenterology and hepatology at the University of Alabama at Birmingham where he also serves on the faculty of the internal medicine residency program. The authors have no conflicts of interest.
REFERENCES
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