Medical Cannabis Authorization and Opioid Milligram Equivalents Over Time In Patients with Chronic Pain: A Retrospective Analysis.

Objective: Strategies are needed for patients with chronic pain who are using opioids to safely and effectively wean opioids without worsening of pain. The objective was to measure associations between medical cannabis authorization and opioid milligram equivalents in patients with chronic non-cancer pain.

Design: A longitudinal, retrospective cohort analysis from July 2016-August 2019.

Setting: Electronic health record data were analyzed.

Subjects: Adult patients (≥ 18 years) seen in a university-based pain clinic.

Methods: Longitudinal multilevel modeling with maximum likelihood estimation.

Results: Average overall opioid milligram equivalent at the final time point was 33.4 mg/day (SE = 1.18) with increase over time, of 0.45 mg/day per quarter (not statistically significant). Average OME in those without medical cannabis authorization was 32.60 mg/day (SE = 1.11); vs. 38.51 mg/day (SE = 4.81) in those with medical cannabis authorization, not significantly different. Medical cannabis consultation predicted a non-significant decrease of 14.25 mg/day opioid milligram equivalent. Long term opioid use was a significant predictor with a mean opioid milligram equivalent of 85.34 mg/day, 63 mg/day higher than the rest of the cohort at the final quarter (t = 5.77, SE = 10.93, p < 0.0001).

Conclusions: In this longitudinal study of electronic health record data, medical cannabis authorization was not associated with a statistically significant decrease in opioid milligram equivalent over time. However, patients with long-term opioid use diagnostic code demonstrated a significantly higher endpoint opioid milligram equivalent. Future prospective research is needed to establish whether there are opioid-sparing effects of cannabis in humans.