Preliminary evaluation of the efficacy, safety, and costs associated with the treatment of chronic pain with medical cannabis

INTRODUCTION: Medical cannabis (MC) is commonly claimed to be an effective treatment for chronic or refractory pain. With interest in MC in the United States growing, as evidenced by the 29 states and 3 US districts that now have public MC programs, the need for clinical evidence supporting this claim has never been greater. METHODS: This was a retrospective, mirror-image study that investigated MC's effectiveness in patients suffering from chronic pain associated with qualifying conditions for MC in New York State. The primary outcome was to compare European Quality of Life 5 Dimension Questionnaire (EQ-5D) and Pain Quality Assessment Scale (PQAS) scores at baseline and 3 months post-therapy. The secondary outcomes included comparisons of monthly analgesic prescription costs and opioid consumption pre- and post-therapy. Tolerability was assessed by side effect incidence. RESULTS: This investigation included 29 subjects. Quality of life and pain improved, measured by change in EQ-5D (Pre 36 – Post 64, P < .0001) and change in PQAS paroxysmal (Pre 6.76 – Post 2.04, P < .0001), surface (Pre 4.20 – Post 1.30, P < .0001), deep (Pre 5.87 – Post 2.03, P < .0001), unpleasant (Pre “miserable” – Post “annoying”, P < .0001). Adverse effects were reported in 10% of subjects. DISCUSSION: After 3 months treatment, MC improved quality of life, reduced pain and opioid use, and lead to cost savings. Large randomized clinical trials are warranted to further evaluate the role of MC in the treatment of chronic pain.