Opioid use in medical cannabis authorization adult patients from 2013 to 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 and 2018 in Alberta, Canada. Methods All adult patients defined as chronic opioid users who were authorized medical cannabis by their health care provider in Alberta, Canada from 2013 to 2018 were propensity score matched to non-authorized chronic opioid using controls. A total of 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 an 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 use, 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.…”

Living Systematic Review on Cannabis and Other Plant-Based Treatments for Chronic Pain – Quarterly Progress Report/Surveillance Report 1: September 2021

“…Six observational studies (N=12,939) reported on the effects of cannabis, with five (3 high, 2 moderate risk of bias) studies evaluating medical cannabis programs, [62][63][64] or self-reported use of cannabis, 65,66 and one moderate risk of bias study evaluating a specific whole-plant cannabis product. 61 Patient characteristics are summarized across studies in Table 5.…”

“…One study evaluated outcomes at 3 months (short duration), 64 and the other five were long duration (1 to 4 years observation). [61][62][63]65,66 The three studies of medical cannabis programs allowed patients to self-select the cannabis products they used and compared them with patients who chose not to enroll in the programs (assumed to be no cannabis use). [61][62][63] Two of the studies are retrospective analyses of larger prospective cohort studies of patients with chronic pain taking opioids, 65,66 based on patient self-report of cannabis use, but specific products used were not reported.…”

“…[61][62][63]65,66 The three studies of medical cannabis programs allowed patients to self-select the cannabis products they used and compared them with patients who chose not to enroll in the programs (assumed to be no cannabis use). [61][62][63] Two of the studies are retrospective analyses of larger prospective cohort studies of patients with chronic pain taking opioids, 65,66 based on patient self-report of cannabis use, but specific products used were not reported. In the study of a whole-plant cannabis product, the cannabis group received herbal cannabis containing 12.5 percent (+/-1.5%) THC.…”

“…Four observational studies reported on the association between cannabis use and opioid use for chronic pain. 62,63,65,66 The studies used different methods and reported outcomes differently, with no consistent direction of effect across the studies. A large, moderate risk of bias, retrospective cohort study (n=10,746) with propensity matching found a nonstatistically significant decrease in weekly oral morphine equivalent (OME) doses in the cannabis group (−183.2 OME, 95% CI −449.8 to 83.3).…”