Abstract and Introduction
Objectives: Despite classic analgesic or effective treatments in rheumatic diseases, such as synthetic DMARDs in RA, patients remain in pain and often turn to non-prescribed pharmacological alternatives, such as cannabis self-therapeutic use. However, this medical use of cannabis has not been thoroughly studied.
Methods: We performed a systematic literature review up to June 2020. The incidence of cannabis consumption was calculated by metaproportion. Differences between cannabis users and non-users were expressed as standardized mean differences using the inverse-variance method. We also assessed the effects of cannabis on pain.
Results: A total of 2900 patients reported cannabis consumption in a sample of 10 873 patients [incidence 40.4% (95% confidence interval (CI): 0.28, 0.54)], and 15.3% (95% CI: 0.07, 0.27) specified that they were currently taking cannabis. Cannabis use was higher in the four fibromyalgia studies [68.2% (95% CI: 0.41, 0.90), n = 611] compared with seven articles concerning RA or lupus [26.0% (95% CI: 0.14, 0.41), n = 8168]. Cannabis consumption was associated with a decrease in pain intensity [VAS pain at baseline 8.2 (2.9) vs 5.6 (3.5) mm over time; pooled effect size −1.75 (95% CI: −2.75, −0.76)]. Cannabis users were younger [58.4 (11.4) vs 63.6 (12.1) years; P <0.001], more often smokers [OR 2.91 (95% CI: 1.84, 4.60)] or unemployed [OR 2.40 (95% CI: 1.31, 4.40)], and had higher pain intensity [5.0 (2.4) vs 4.1(2.6) mm; P <0.001] than non-users.
Conclusion: Nearly 20% of patients suffering from rheumatologic diseases actively consume cannabis, with an improvement in pain. The issue of cannabis use in the management of these patients should be addressed during medical consultation, essentially with cannabis-based standardized pharmaceutical products.
Rheumatic diseases, such as RA and ankylosing spondylitis, are characterized by synovitis, causing pain and disability. The number of disease-modifying anti-rheumatic drugs is increasing, with TNF-alpha inhibitors, methotrexate, and IL6 inhibitors allowing better control of disease activity and more frequent clinical remission. This clinical remission is mostly associated with reduced pain. In addition, JAK inhibitors were recently reported to rapidly decrease patient-reported pain.[1,2] However, despite effective treatments for rheumatic disease and clinical remission, some patients still report pain of high intensity that affects their quality of life.
In the same way, other rheumatologic diseases, such as fibromyalgia, degenerative back pain, and OA, suffer from a lack of effective treatments and cause pain that is hardly relieved by conventional analgesic treatments. Therefore, it is not uncommon that patients suffering from these rheumatic diseases admit during consultation to taking pharmacological alternative treatments, such as a self-therapeutic cannabis use, to relieve their pain.
Several studies have shown an interesting effect of cannabis as an adjuvant treatment in chronic diseases, such as Parkinson's and multiple sclerosis, to improve symptoms.[3–6] Recently, application of transdermal cannabidiol was shown to decrease pain in temporomandibular disorders. In a meta-analysis of chronic non-cancer pain (neuropathic pain, central pain in multiple sclerosis, and one study on RA), Lynch et al. concluded that cannabis demonstrates a significant analgesic effect compared with placebo, with significant improvement in sleep. In rheumatology, the number of studies assessing the effects of cannabis in patients with RA or OA is low. In animal studies, cannabis has been associated with a decrease in OA pain in rats and an increase in comfort and activity in dogs with OA.[9,10] In a previous meta-analysis in 2016, Fitzcharles et al. only found four randomized controlled trials assessing the efficacy and safety of cannabis in RA, OA or fibromyalgia, and no article was useful for quantitative analysis. However, the medical community is well aware that cannabis could have an interesting effect. An editorial and another article by Fitzcharles et al. recently recalled the potential effects of cannabis in rheumatology, but also warns of the need for medical supervision in cannabis use, and that more studies are needed.[12,13]
We performed a meta-analysis of published studies or abstracts to better estimate the incidence of cannabis consumption, assess the effects of cannabis on pain in patients suffering from rheumatologic diseases, and compare the characteristics of cannabis users to those of non-users.
Rheumatology. 2021;60(2):549-556. © 2021 Oxford University Press