Introduction: Cannabinoids have been legalized for medicinal use in Australia and interest in its use grows. Despite its popularity, there is insufficient evidence to support prescribers using it in the context of rheumatic diseases.
Aim: To determine the safety, efficacy and tolerability of cannabinoids in patients with rheumatism.
Methods: We performed a systematic review of Medline, Embase and Evidence-based reviews databases for randomized controlled trials (RCTs) and observational studies with at least one outcome of efficacy, safety or tolerability. Each study was evaluated using the Cochrane risk of bias tool.
Results: Seven RCTs (n=58 rheumatoid arthritis, n=24 temporo-mandibular-joint osteoarthritis, n=185 knee osteoarthritis, n=97 fibromyalgia) and 5 cohort studies (n=676 fibromyalgia) were identified that assessed pain, sleep, anxiety and/or quality of life. A high risk of bias was found in 3/7 RCTs and 4/5 cohort studies; an unclear risk of bias in 3/7 RCTs and in 1/5 cohort studies. One RCT was prematurely terminated. Nine cannabinoid formulations were assessed and a statistically significant effect was found in 5 for pain, in 2 for sleep quality, and in 2 for stress. All cannabinoid formulations had mild/moderate adverse effects (e.g. dizziness, drowsiness, nausea, dry mouth) with the exception of palmitoylethanolamide that had none. Due to study heterogeneity, a meta-analysis could not be performed.
Conclusions: The smaller studies do not provide strong evidence as to the usefulness of cannabinoids in rheumatic diseases. There is however a potential therapeutic benefit with cannabinoids in alleviating pain and improving sleep quality, particularly in patients with fibromyalgia. The studies investigating palmitoylethanolamide suggested a safe and efficacious drug. A large, focused study on palmitoylethanolamide in the context of osteoarthritis or fibromyalgia is recommended.