Prevalence and correlates of intentional substance use to reduce illicit opioid use in a Canadian setting

ABSTRACT

Background

While preliminary evidence has begun to document intentional use of one substance to reduce the use of another, the phenomenon of drug substitution among people who use illicit opioids remains understudied. Therefore, we sought to estimate the prevalence and correlates of intentional substance use to reduce illicit opioid use among persons who use drugs (PWUD).

Methods

We analyzed data from three prospective cohorts of PWUD in Vancouver, Canada, using multivariable generalized estimating equations (GEE).

Results

Between June 2012 and June 2016, 1527 participants were recruited and contributed 4991 interviews. Of those, 336 (22%) illicit opioid-using participants self-reported substitution to reduce illicit opioid use at least once during study period contributing 467 (9.4%) interviews. Among those interviews, substances substituted for opioids were alcohol (15 participants, 3.2%), stimulants (235, 50.3%), cannabis (129, 27.6%), benzodiazepines (21, 4.5%), and others (20, 4.3%). In multivariable GEE model adjusted for socio-demographic factors, reporting substitution to reduce illicit opioid use was positively associated with greater likelihood of daily cannabis use (Adjusted Odds Ratio = 1.56, 95% Confidence Interval: 1.24–1.96].

Conclusions

While daily cannabis use was associated with reporting opioid substitution attempts, additional study is needed to examine potential of cannabis/cannabinoids to reduce illicit opioid use.

KEYWORDS:

• Cannabis
• opioids
• substance related disorders
• longitudinal observation

Acknowledgments

The authors thank the study participants for their contribution to the research, as well as current and past researchers and staff.

Disclosure statement

The University of British Columbia (UBC) has received an unstructured gift to support M.-J Milloy’s research from NG Biomed, Ltd., an applicant to the Canadian federal government for a license to produce medical cannabis. Dr. Milloy is the Canopy Growth professor of cannabis science at UBC, a position created by an unstructured gift to the university from Canopy Growth, a licensed producer of cannabis, and the Government of British Columbia’s Ministry of Mental Health and Addictions. No other potential conflict of interest interest was reported by the author(s).

Data statement

Due to the nature of this research, participants of this study did not agree for their data to be shared publicly, so supporting data is not available.

Additional information

Funding

US National Institutes of Health supported the study [R01DA011591, U01DA021525, U01DA038886]. This research was also undertaken, in part, by funding from the Canada Research Chairs program through a Tier 1 Canada Research Chair in Inner City Medicine, and by the US National Institutes of Health [R25DA037756] that supports Dr. Evan Wood. The study was supported by the Canadian Institutes of Health Research [MOP–286532, 397968, 422332]. Dr. Milloy is supported by the United States National Institutes of Health [U01-DA021525], a New Investigator award from the Canadian Institutes of Health Research and a Scholar award from the Michael Smith Foundation for Health Research. His institution has received an unstructured gift from NG Biomed, Ltd., a private firm applying for a licence to produce medical cannabis, to support him. He is the Canopy Growth professor of cannabis science at the University of British Columbia, a position established through arms length gifts to the university from Canopy Growth, a licensed producer of cannabis, and the Government of British Columbia’s Ministry of Mental Health and Addictions. Dr Jan Klimas’ work on this paper has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 701698; and from the Canadian Institutes of Health Research [FRN165004]. Dr. Kanna Hayashi is supported by a Canadian Institutes of Health Research New Investigator [MSH-141971], a Michael Smith Foundation for Health Research (MSFHR) Scholar Award, and the St. Paul’s Foundation. Dr. M. Eugenia Socías is supported by a Michael Smith Foundation for Health Research (MSFHR)/St Paul’s Foundation Scholar Award. Stephanie Lake is supported by doctoral scholarships from the Canadian Institutes of Health Research (CIHR) and the Pierre Elliott Trudeau Foundation.