This review examines evidence for the effectiveness of cannabinoids in chronic noncancer pain (CNCP) and addresses gaps in the literature by: considering differences in outcomes based on cannabinoid type and specific CNCP condition; including all study designs; and following IMMPACT guidelines. MEDLINE, Embase, PsycINFO, CENTRAL, and clinicaltrials.gov were searched in July 2017. Analyses were conducted using Revman 5.3 and Stata 15.0. A total of 91 publications containing 104 studies were eligible (n = 9958 participants), including 47 randomised controlled trials (RCTs) and 57 observational studies. Forty-eight studies examined neuropathic pain, 7 studies examined fibromyalgia, 1 rheumatoid arthritis, and 48 other CNCP (13 multiple sclerosis-related pain, 6 visceral pain, and 29 samples with mixed or undefined CNCP). Across RCTs, pooled event rates (PERs) for 30% reduction in pain were 29.0% (cannabinoids) vs 25.9% (placebo); significant effect for cannabinoids was found; number needed to treat to benefit was 24 (95% confidence interval [CI] 15-61); for 50% reduction in pain, PERs were 18.2% vs 14.4%; no significant difference was observed. Pooled change in pain intensity (standardised mean difference: -0.14, 95% CI -0.20 to -0.08) was equivalent to a 3 mm reduction on a 100 mm visual analogue scale greater than placebo groups. In RCTs, PERs for all-cause adverse events were 81.2% vs 66.2%; number needed to treat to harm: 6 (95% CI 5-8). There were no significant impacts on physical or emotional functioning, and low-quality evidence of improved sleep and patient global impression of change. Evidence for effectiveness of cannabinoids in CNCP is limited. Effects suggest that number needed to treat to benefit is high, and number needed to treat to harm is low, with limited impact on other domains. It seems unlikely that cannabinoids are highly effective medicines for CNCP.
Probably the most comprehensive SR to date. Given the headlong rush to legalize and proliferate cannabis in many countries, this summary of evidence is extremely useful.
"...NNTB is high, with NNTH low..." It's interesting to see the evidence of benefit is so weak with all the hype around.
Not a particularly useful study, but that is the state of the art.
An excellent meta-analysis that provides clinicians some estimates of the expected benefit when using cannabis to treat chronic noncancer pain. I believe this article will help general internists have more meaningful conversations with their patients about using marijuana for pain control.
This article should but probably won't dispel the widespread uncritical thinking that medical marijuana will provide effective and safe treatment for chronic non-cancer pain.
The proliferation of medically and legislatively sanctioned marijuana use absent clear evidence of benefit has long been a concern of mine and indeed, I believe it is a public health concern that is being inadequately confronted by the medical community. This article is a well-done and compelling contribution to the literature at least insofar as non-cancer chronic pain. State medical societies and physicians should be sure our legislators are aware of the medical facts regarding which conditions clearly benefit (as indeed some do) from access to medical marijuana and which ones do not and are being influenced by other social factors and advocacy groups.
Excellent article that will add to the controversy regarding medical marijuana and chronic pain treatment.