New data from the US has shown medicinal cannabis use decreased in states where recreational use became legal .
Researchers from the University of Michigan Medical School and the Centres for Disease Control and Prevention found that, while enrolment in medicinal cannabis programs increased overall between 2016 and 2022, it fell in states where non-medical use became legal.
The researchers conducted an ecological study with repeated measures of people with medical cannabis licences and clinicians authorising cannabis licences in the US between 2020 and 2022.
The authors included 39 jurisdictions (38 states and Washington D.C.) that allowed for medical cannabis use in their analysis.
Of these, 34 reported patient numbers, 19 cited patient-reported qualifying conditions, and 29 reported authorising clinician numbers.
Overall, they reported a 33 per cent increase in patient enrolment in these jurisdictions between 2020 (3.1 million) and 2022 (4.1 million).
However, within the 15 jurisdictions with active adult-use laws, 13 had decreasing enrolment.
From 2020-2022, the proportion of patient-reported qualifying conditions with substantial or conclusive evidence of therapeutic value decreased from 70.4 to 53.8 per cent. The most reported qualifying condition was chronic pain, followed by anxiety and post-traumatic stress disorder.
The study is published in Annals of Internal Medicine.
Combined with data from a previously published analysis, the number of patients using cannabis for medical purposes has increased by more than 600 per cent since 2016.
Cannabis is legal for medical or non-medical adult use in 38 and 23 US states respectively.
While it remains a schedule I substance under the Controlled Substances Act, a status which has inhibited research on its health effects and discouraged physicians from pursuing it as a treatment option, the Department of Health and Human Services recently recommended it be rescheduled to schedule III.
