Cannabis and liver transplant in the era of legalization: Effects of pre-transplant cannabis use on postoperative opioid use and transplant outcomes.

Background: Cannabis use is increasing in the United States, including among liver transplant candidates. Although the anesthesia literature suggests an association between cannabis use and increased post-operative pain, the impact of cannabis use on post-liver transplant (LT) opioid use remains unknown. This study investigates changes in cannabis use at a transplant center over time, as well as the impact of cannabis use on post-LT opioid use, healthcare utilization, and mortality.

Methods: We included 4,236 patients evaluated for LT at our institution between January 2013 and July 2023. Our primary risk factor was cannabis use, defined as urine toxicology (UTox) positive for cannabis within 90 days of LT evaluation. Our primary outcome was post-LT opioid use, including oral morphine equivalents (OME) received during the LT hospitalization and discharge opioid prescriptions. We used multivariable logistic and quantile regression to compare post-LT opioid use, healthcare utilization outcomes, and mortality between cannabis users and nonusers.

Results: Cannabis use was associated with higher OME use in the 48 hours post-LT (p=0.04). There were no statistically significant differences between groups in 72-hour (p=0.07) or 7-day cumulative OME (p=0.33), opioid prescriptions on discharge (p=0.25), hospital length of stay (LOS, p=0.69), intensive care unit LOS (p=0.94), 90-day readmission (p=0.66), or 90-day mortality (p=0.96).

Conclusions: While cannabis use pre-LT was associated with significantly higher opioid use in the immediate postoperative period, this did not translate to differences in opioid use beyond 48 hours post-LT, or short-term healthcare utilization or clinical outcomes. These findings should help set provider expectations for immediate post-LT pain control. Our findings support the growing body of literature that fails to identify an association between pre-LT cannabis use and post-LT outcomes.