Opioid Use in Medical Cannabis Authorization Adult Patients from 2013-2018: Alberta, Canada

Abstract

Background: The opioid overdose epidemic in Canada and the United States has become a public health crisis - with exponential increases in opioid-related morbidity and mortality. Recently, there has been an increasing body of evidence focusing on the opioid-sparing effects of medical cannabis use (reduction of opioid use and reliance), and medical cannabis as a potential alternative treatment for chronic pain. The objective of this study is to assess the effect of medical cannabis authorization on opioid use (oral morphine equivalent; OME) between 2013-2018 in Alberta, Canada.Methods: All adult patients defined as chronic opioid users who received medical cannabis authorization in the province of Alberta from 2013-2018 were propensity score matched to non-authorized chronic opioid using controls. 5373 medical cannabis patients were matched to controls, who were all chronic opioid users. The change in the weekly average OME of opioid drugs for medical cannabis patients relative to controls was measured. Interrupted time series (ITS) analyses was used to assess the trend change in OME during the 26 weeks (6 months) before and 52 weeks (1 year) after the authorization of medical cannabis among adult chronic opioid users.Results: Average age was 52 years and 54% were female. Patients on low dose opioids (<50 OME) had a slightly increase in their weekly OME per week (absolute increase of 112.1 OME, 95% CI: 104.1 to 120.3); whereas higher dose users (OME >100), showed a significant decrease over 6 months (-435.5, 95% CI: -596.8 to -274.2) compared to controls. Conclusions: This short-term study found that medical cannabis authorization showed intermediate effects on opioid utilization, which was dependent on initial opioid use. Greater observations of changes in OME appear to be in those patients who were on a high dosage of opioids (OME>100); however, continued surveillance of patients utilizing both opioids and medical cannabis – is warranted by clinicians to understand the long-term potential benefits and any harms of ongoing use.

Gaps in evidence for the use of medically authorized cannabis: Ontario and Alberta, Canada

“…For example, pain was one of the highest conditions noted where medical cannabis is being used in this cohort of patients. We have previously shown that cannabis may have important impacts to help reduce the use of opioids for chronic pain at the population level [35]. Thus, medical cannabis authorization could be a potential strategy to minimize harm associated with opioid use.…”