Cannabinoids somewhat helpful for nausea, maybe helpful for spasticity, probably not helpful for non-neuropathic pain

Reference

Allan GM, Finley CR, Ton J, et al. Systematic review of systematic reviews for medical cannabinoids: Pain, nausea and vomiting, spasticity, and harms. Can Fam Physician 2018;64: e78-e94.

Synopsis

This is an umbrella review, which is a systematic review of systematic reviews. The authors did a broad search and identified 31 systematic reviews of the benefits and harms of cannabinoids, each with at least 2 randomized controlled trials. The topics addressed included pain, nausea and vomiting, spasticity, and adverse events. Individual outcomes were addressed in between 2 and 28 studies and in 44 to 2737 patients. Challenges of this approach include a variety of populations, interventions, doses, and comparators, as well as the challenge of masking patients to treatment assignment. Most meta-analyses found a modest benefit, approximately 0.4 to 0.8 points, compared with placebo. Such a small benefit is unlikely to be clinically meaningful, as we usually look for at least a 1-point improvement on a 10-point scale. Studies were moderately heterogeneous, with approximately half finding some benefit and half finding no benefit (I2 = 43%). Benefit was generally greater in studies of neuropathic pain. Studies on the treatment of nausea and vomiting primarily included chemotherapy patients and those receiving palliative care (number needed to treat [NNT] = 3 - 7). Again, there was significant heterogeneity. There was some evidence of benefit for treatment of spasticity as measured by the outcome of responder versus nonresponder (NNT = 7 - 10), although the reductions in a 10-point spasticity score were modest (0.31 - 0.76). Adverse events such as feeling high, disorientation, and confusion were relatively common (number needed to treat to harm [NNTH] = 2 - 15), though psychosis was relatively rare. The NNTH to discontinue the medication was between 8 and 22.