Use of medical cannabis by patients with fibromyalgia in Canada after cannabis legalisation: a cross-sectional study

Objectives: Medications have only small to moderate effects on symptoms in fibromyalgia (FM). Cannabinoids, including medical cannabis (MC) may have potential to fill this gap. Since recreational legalisation of cannabis in Canada, patients have easier access and may be self-medicating with cannabis. We have examined the prevalence and characteristics of MC use in FM patients.

Methods: During a two-month period (June-August 2019), consecutive attending rheumatology patients participated in an onsite survey comprising 2 questionnaires: 1) demographic and disease information completed by the rheumatologist, 2) patient anonymous questionnaire of health status, cannabis use (recreational and/or medicinal) and characteristics of use.

Results: In a cohort of 1000 rheumatology attendees, 117 (11.7%) were diagnosed with FM. Ever use of MC was reported by 28 (23.9%; 95%CI: 16.5%-32.7%) FM patients compared to 98 (11.1%; 95%CI: 9.1%-13.4%) non-FM patients. Among FM ever users, 17 (61%) patients continued use of MC. FM ever users vs. FM nonusers tended to be younger, 53 vs. 58 years (p=0.072), were more likely unemployed or disabled 39% vs. 17% (p=0.019) and used more medication types (p=0.013) but did not differ in symptom severity parameters. Cigarette smoking and recreational cannabis were more common in ever users. Global symptom relief on a VAS (1-10) was 7.0±2.3.

Conclusions: FM patients have commonly used MC, with more than half continuing use. Reported symptom relief was substantial. Cigarette smoking and recreational cannabis use may play a facilitatory role in MC use in FM. Adjunctive MC may be a treatment consideration for some FM patients.