Observational Study of Medicinal Cannabis for Chronic Pain Finds Reductions in Pain, Disability, and Prescribed Opioid Use

Some evidence supports the efficacy of cannabis for the treatment of chronic pain, but few studies extend beyond weeks. Israeli patients with “treatment-resistant chronic pain” were prescribed medicinal cannabis and encouraged to taper opioid medications in this open-label, prospective case series, which provided 7-month follow-up outcomes including pain intensity, functional outcomes, satisfaction, and opioid medication use. Pain and quality of life were assessed with the S-TOPS (Treatment Outcomes of Pain Survey–Short Form) and the BPI (Brief Pain Inventory).

• 206 patients were followed in an intention-to-treat (ITT) sample and 176 completed full per-protocol (PP) follow-up data collection.
• Patients’ median S-TOPS pain symptom score decreased from 83 to 75 at follow-up, similar to the changes in the results of the BPI for both pain severity (median score decreased from 7.50 to 6.25) and pain interference (median score decreased from 8.14 to 6.71). ITT and PP analyses were similar.
• Of 73 patients with opioid use at baseline, 32 discontinued opioids at follow-up. The median oral morphine equivalent dose among those still receiving opioids decreased from 60 mg to 45 mg, but the change was not significant.

Comments: While these findings support a small potential improvement in chronic pain outcomes and reduction in prescribed opioids with the administration of medicinal cannabis, the observational nature of the study means that placebo effect or regression to the mean are possible alternative explanations. Patients were excluded for prior addiction history or risk of addiction, eliminating from the analysis those most likely to be harmed by cannabis and perhaps most likely to seek out such treatment. Lastly, patients were followed for months, not years, similar to prior studies of opioids for chronic pain conditions that failed to identify key safety problems.

Joseph Merrill, MD, MPH

Reference: Haroutounian S, Ratz Y, Ginosar Y, et al. The effect of medicinal cannabis on pain and quality-of-life outcomes in chronic pain: a prospective open-label study. Clin J Pain. 2016;32:1036–1043.