Background/Purpose:  With a worldwide groundswell of interest in cannabinoids as a possible treatment option for persons with rheumatic diseases, and with few pharmacologic cannabinoid options available, patients may be using marijuana mostly to self-medicate.  “Severe arthritis” was cited as the diagnosis for 65% of persons legally authorized to possess medicinal marijuana in Canada in 2014. With knowledge that most medicinal marijuana is obtained illegally, and by extrapolating from Canadian census data of 2011, conservative estimates are that 4% of persons with rheumatic complaints may be using cannabis, with an even higher rate expected for those in rheumatology care. As there is currently no knowledge of the prevalence of use of marijuana in a defined rheumatology population, we have prospectively examined the use of herbal cannabis for 1000 rheumatology attenders.

Methods:  The study was approved by the Institutional Ethical Review board and informed consent was obtained from every participant. During a two month period (April-May 2014), consecutive patients attending an academic, community based rheumatology clinic staffed by 3 rheumatologists were invited to participate. Patients were either newly referred or attending for a follow up visit.  The study comprised 2 questionnaires completed at the time of the visit: 1) demographic and disease related information completed by the rheumatologist, 2) patient anonymous report of current health status, pain severity and past or current marijuana use for either recreational or medicinal purposes, or both.

Results: Of the 1067 patients attending, 1000 (96%; 74% females; mean age 63 ± 15 yrs) agreed to participate. Thirty seven patients refused to participate and 30 were not eligible. Disease categories were as follows: inflammatory arthritis 516 (52%), osteoarthritis or back pain, 489(49%) soft tissue rheumatism or fibromyalgia, 218 (22%), and other condition, 99(10%) with some overlap of diagnoses. Medicinal marijuana was reportedly used by 28 patients (2.8%; 95% CI: 1.9-4.2). Users vs. non users were more likely to be younger, 53.vs.63 yrs (p=0.0003), unemployed or disabled 46% vs. 8% (p<0.0001), and with a trend to be male. Diagnoses did not differ between the users and nonusers, but users reported poorer global well-being 5.5 vs. 3.9 (p=0.0029), more pain 6.3 vs 4.8 (p= 0.0088), and previous recreational cannabis use 82% vs 19% (p< 0.0001). The Physician global assessment of health status did not differ significantly between the groups 3.2 vs 2.8 (p=0.2991). 

Conclusion:  Contrary to the expected rate, only 2.8% of patients, receiving rheumatology care for multiple rheumatic disease categories, reported current use of medicinal marijuana. With use observed across all disease categories, familiarity with marijuana as a recreational product may explain use for some. Perceived health status was poorer for users, with almost half not working.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/prevalence-of-medicinal-marijuana-use-among-1000-rheumatology-patients-attending-a-community-based-rheumatology-clinic-a-prospective-cross-sectional-study/