More people are using medical cannabis as it becomes legal in more states, but the lack of standardization in states’ data collection hindered investigators’ efforts to track that use.

Legalized medical cannabis is now available in 33 states and the District of Columbia, and the number of users has risen from just over 72,000 in 2009 to almost 814,000 in 2017. That 814,000, however, covers only 16 states and D.C., since 1 state (Connecticut) does not publish reports on medical cannabis use, 12 did not have statistics available, 2 (New York and Vermont) didn’t report data for 2017, and 2 (California and Maine) have voluntary registries that are unlikely to be accurate, according to Kevin F. Boehnke, PhD, of the University of Michigan, Ann Arbor, and his associates.

Michigan had the largest reported number of patients enrolled in its medical cannabis program in 2017, almost 270,000. California – the state with the oldest medical cannabis legislation (passed in 1996) and the largest overall population but a voluntary cannabis registry – reported its highest number of enrollees, 12,659, in 2009-2010, the investigators said. Colorado had more than 116,000 patients in its medical cannabis program in 2010 (Health Aff. 2019;38[2]:295-302).

The “many inconsistencies in data quality across states [suggest] the need for further standardization of data collection. Such standardization would add transparency to understanding how medical cannabis programs are used, which would help guide both research and policy needs,” Dr. Boehnke and his associates wrote.

More consistency was seen in the reasons for using medical cannabis. Chronic pain made up 62.2% of all qualifying conditions reported by patients during 1999-2016, with the annual average varying between 33.3% and 73%. Multiple sclerosis spasticity symptoms had the second-highest number of reports over the study period, followed by chemotherapy-induced nausea and vomiting, posttraumatic stress disorder, and cancer, they reported.

The investigators also looked at the appropriateness of cannabis and determined that its use in 85.5% of patient-reported conditions was “supported by conclusive or substantial evidence of therapeutic effectiveness, according to the 2017 National Academies report” on the health effects of cannabis.

“We believe not only that it is inappropriate for cannabis to remain a Schedule I substance, but also that state and federal policy makers should begin evaluating evidence-based ways for safely integrating cannabis research and products into the health care system,” they concluded.

SOURCE: Boehnke KF et al. Health Aff. 2019;38(2):295-302.