Medical cannabis authorization and opioid milligram equivalents over time in patients with chronic pain: a retrospective analysis

Abstract

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 (MCA) and opioid milligram equivalents (OME) in patients with chronic non-cancer pain. Design: A longitudinal, retrospective cohort analysis from July 2016 to August 2019. Setting: Electronic health record data were analyzed. Subjects: Adult patients (≥ 18years) seen in a university-based pain clinic. Methods: Longitudinal multilevel modeling with maximum likelihood estimation. Results: Average overall OME 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 MCA was 32.60 mg/day (SE = 1.11) versus 38.51 mg/day (SE = 4.81) in those with MCA, not significantly different. Medical cannabis consultation predicted a nonsignificant decrease of 14.25 mg/day OME. Long-term opioid use was a significant predictor with a mean OME 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, MCA was not associated with a statistically significant decrease in OME over time. However, patients with long-term opioid use diagnostic code demonstrated a significantly higher endpoint OME. Future prospective research is needed to establish whether there are opioid-sparing effects of cannabis in humans.