“No Evidence” That Cannabis Eases Chronic Pain

Researchers found no evidence that cannabis use improved symptoms of chronic pain in a 4-year study of individuals with chronic non-cancer pain.

Due to its potential to reduce opioid dose requirements, there is increased interest in the use cannabis and cannabinoids for the treatment of chronic non-cancer pain.

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For their study, the researchers sought to investigate reasons for and perceived effectiveness of cannabis in individuals with chronic pain who had been prescribed opioids. The association between amount of cannabis used and pain, mental health, and opioid use, as well as the effect of cannabis use on pain severity and the potential opioid-sparing effects of cannabis were also examined.

Participants in the study (N = 1514) were recruited through community pharmacies in Australia. All participants completed a baseline interview and were followed-up with phone interviews or self-complete questionnaires yearly for 4 years. The participants reported lifetime and past year chronic pain, duration of chronic pain, pain self-efficacy, whether the pain was neuropathic, lifetime and past 12-month cannabis use, and current depression and generalized anxiety disorder.

Logistic regression was used to investigate cross-sectional associations with frequency of cannabis use, while lagged mixed-effects models were used to examine temporal associations between cannabis and outcomes.

Overall, by 4-year follow-up, 295 (24%) of participants had used cannabis for pain, with interest in using cannabis for pain increasing from 364 (33%) at baseline to 723 (60%) at 4 years.

The researchers found that those who used cannabis had greater pain severity score, greater pain interference score, lower pain self-efficacy scores, and greater generalized anxiety disorder severity scores. No evidence of a temporal relationship between cannabis and pain severity or pain interference, or that cannabis reduced prescribed opioid use, was found.

“In conclusion, cannabis use is common in people with chronic non-cancer pain who have been prescribed opioids, and interest in medicinal use of cannabis is increasing. We found no evidence that cannabis use improved patient outcomes; those who used cannabis had greater pain and lower self-efficacy in managing pain. Furthermore, we found no evidence that cannabis use reduced pain interference or exerted an opioid-sparing effect.”

—Michael Potts

Reference:

Campbell G, Hall WD, Peacock A, et al. Effect of cannabis use in people with chronic non-cancer pain prescribed opioids: findings from a 4-year prospective cohort study [published online July 2018]. Lancet Public Health. https://doi.org/10.1016/S2468-2667(18)30110-5.