Does Routine Use of Medical Cannabis (Marijuana) Decrease the Intensity of Chronic Neuropathic Pain in Adults?

OBJECTIVE: The objective of this selective EBM was to investigate the question, “Does routine use of medical cannabis (marijuana) decrease the intensity of neuropathic chronic pain in adults? STUDY DESIGN: systematic review of 3 English language primary studies, published between 2005 and 2009. DATA SOURCES: Three Randomized Controlled Trials (RTC’s) published on or after 2005 were selected based on their relevance to the proposed question via PubMed. All three RTC’s compared cannabis use vs. placebo for chronic neuropathic pain, with two RTC’s focusing on HIV neuropathic pain and the third focusing on MS. OUTCOMES MEASURED: The outcomes measured in these trials were by how much medical cannabis decreases the intensity of chronic neuropathic pain. This was accomplished using three techniques depending on the study: A self-reporting visual analog scale; a Descriptor Differential Scale (DDS); and an 11-point numerical sliding scale. RESULTS: Ronald Ellis and co-authors demonstrated that the proportions of subjects with HIV achieving at least 30% pain relief with cannabis versus placebo were 0.46 (95%CI 0.28, 0.65) and 0.18 (0.03, 0.32). Abrams and co-authors demonstrated that smoked cannabis reduced daily pain with HIV by 34% vs 17% with placebo (p= 0.03). Greater than 30% reduction in pain was reported by 52% in the cannabis group and by 24% in the placebo group (p= 0.04). Rog and coauthors demonstrated that cannabis was superior to placebo in reducing the mean intensity of pain of MS (CBM mean change -2.7, 95% CI: -3.4 to -2.0, placebo –1.4 95% CI: -2.0 to -0.8, comparison between groups, p =0.005). CONCLUSIONS: There is a significant benefit to patients with chronic neuropathic pain when using medical cannabis vs. placebo in HIV and MS. While the risks and benefits to daily use of medical marijuana needs to be further investigated, medical cannabis can be an effective alternative to standard treatments in those who can’t tolerate their side effects. OBJECTIVE