Efficacy, tolerability and safety of cannabinoids in chronic pain associated with rheumatic diseases (fibromyalgia syndrome, back pain, osteoarthritis, rheumatoid arthritis): A systematic review of randomized controlled trials.

Background: In the absence of an ideal treatment for chronic pain associated with rheumatic diseases, there is interest in the potential effects of cannabinoid molecules, particularly in the context of global interest in the legalization of herbal cannabis for medicinal use. Methods: A systematic search until April 2015 was conducted in Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, www.cannabis-med.org and clinicaltrials.gov for randomized controlled trials with a study duration of at least 2 weeks and at least ten patients per treatment arm with herbal cannabis or pharmaceutical cannabinoid products in fibromyalgia syndrome (FMS), osteoarthritis (OA), chronic spinal pain, and rheumatoid arthritis (RA) pain. Outcomes were reduction of pain, sleep problems, fatigue and limitations of quality of life for efficacy, dropout rates due to adverse events for tolerability, and serious adverse events for safety. The methodology quality of the randomized controlled trials (RCTs) was evaluated by the Cochrane Risk of Bias Tool. Results: Two RCTs of 2 and 4 weeks duration respectively with nabilone, including 71 FMS patients, one 4-week trial with nabilone, including 30 spinal pain patients, and one 5-week study with tetrahydrocannbinol/cannabidiol, including 58 RA patients were included. One inclusion criterion was pain refractory to conventional treatment in three studies. No RCT with OA patients was found. The risk of bias was high for three studies. The findings of a superiority of cannabinoids over controls (placebo, amitriptyline) were not consistent. Cannabinoids were generally well tolerated despite some troublesome side effects and safe during the study duration. Conclusions: Currently, there is insufficient evidence for recommendation for any cannabinoid preparations for symptom management in patients with chronic pain associated with rheumatic diseases.