Comparative safety analysis of nabilone versus opioids: a population-based cohort study

Background — Some have advocated that nabilone be used rather than opioids to manage chronic, noncancer pain, since the former drug may have a better safety profile.

Objective — We compared the safety of incident nabilone use relative to incident opioid use with respect to multiple clinically important outcomes.

Design — A population-based, retrospective cohort study.

Setting — Province of Ontario, Canada.

Participants — Persons aged 12 years and older, diagnosed with a musculoskeletal condition within the past 3 years prior to the index date.

Exposures — Incident nabilone use, with incident opioid use serving as the reference group.

Measurements — Within 3 months following the index date, we separately evaluated for pneumonia, motor vehicle accidents, falls or fractures, mental and behavioral disorder due to psychoactive substance use, and all-cause mortality.

Results — A total of 18,863 incident nabilone users were propensity score matched to an equal number of opioid users. In the overall matched analysis, incident nabilone users vs. incident opioid users had significantly lower rates of pneumonia (hazard ratio [HR] 0.78, 95% CI 0.63-0.96), falls or fractures (HR 0.56, 95% CI 0.50-0.64), and all-cause mortality (HR 0.79, 95% CI 0.65-0.95), but significantly higher rate of mental or behavioral disorder (HR 2.23, 95% CI 1.45-3.43). There was no significant difference between groups with respect to rate of motor vehicle accidents.

Limitations — Unmeasured confounding may have influenced results.

Conclusions — While usage of nabilone relative to opioids was associated with reduced rates of pneumonia, falls or fractures, and all-cause mortality, it was simultaneously associated with an increased rate of adverse mental health outcomes. This picture of mixed safety results raises concerns with the policy approach of broadly substituting use of opioids with nabilone.