An observational study has found that the number of patients enrolled in medical cannabis programs has increased four-fold between 2016 and 2020. The trend has been driven by a combination of new medical cannabis laws in 35 states, expanded qualifying conditions, and increased enrollment nationally. The findings are published in Annals of Internal Medicine.

Since 1996, 37 states have legalized the use of medical cannabis and 18 have legalized the use of recreational cannabis for adults. The ongoing conflict between state legalization and federal restriction creates medical and legal uncertainty for both users and clinicians.

Researchers from the University of Michigan Medical School analyzed medical cannabis program registry data from Washington, D.C. and 35 states to describe recent trends in medical cannabis licensure in the United States. The authors found that between 2016 and 2020, the national number of patients enrolled in medical cannabis programs increased from 678,408 in 2016 to 2,974,433 in 2020. Chronic pain was the most common patient-reported qualifying condition, accounting for 60.6 percent of all available data. Post-traumatic stress disorder (PTSD) was the second most common patient-reported qualifying condition, accounting for 10.6 percent of total data.

The authors note that these conditions were more common in medical-only states, while states allowing recreational use reported comparably higher percentages of patients reporting experiencing multiple sclerosis, arthritis, and chemotherapy-induced nausea and vomiting. According to the authors, their findings highlight the value of aligned federal and state cannabis regulation. They note that changing the federal schedule 1 designation for cannabis would provide opportunities to create regulation that would improve state policies and labeling and potency testing, clarify legal and medical discrepancies, and ensure appropriate training for dispensary employees and health care professionals.