Prevalence of Heavy Alcohol Use Among People Receiving Methadone Following Change to Methadose

ABSTRACT

Background: A recent switch in methadone formulation from methadone (1 mg/mL) to Methadose (10 mg/mL) in British Columbia (BC), Canada, was associated with increased reports of opioid withdrawal and increases in illicit opioid use. Impacts on other forms of drug use have not been assessed. Since alcohol use is common among people receiving Medication-Assisted Treatment (MAT), we assessed if switch was associated with increased prevalence of heavy alcohol use. Methods: Drawing on data from two open prospective cohort studies of people who inject drugs in Vancouver, BC, generalized estimating equations (GEE) model examined relationship between methadone formulation change and heavy alcohol use, defined by National Institute for Alcohol Abuse and Alcoholism (NIAAA). A sub-analysis examined relationship with heavier drinking defined as at least eight drinks per day on average in last six months. Results: Between June 2013 and May 2015, a total of 787 participants on methadone were eligible for the present analysis, of which 123 (15.6%) reported heavy drinking at least once in last six months. In an unadjusted GEE model, Methadose use was not significantly associated with an increased likelihood of heavy drinking [Odds Ratio (OR) = 1.03; 95% Confidence interval (CI) = 0.87–1.21]. Methadose use was not significantly associated with an increased likelihood of drinking at least eight drinks daily on average (OR = 1.09, 95% CI = 0.72–1.65). Conclusions: Despite reported changes in opioid use patterns coinciding with the change, there appeared to be no effect of the methadone formulation change on heavy drinking in this setting.

KEYWORDS:

• Alcohol
• methadone maintenance treatment
• heroin
• longitudinal study
• formulation: medication assisted treatment (MAT)
• opioid use disorder

Acknowledgments

The authors thank the study participants for their contribution to the research, as well as current and past researchers and staff. US National Institutes of Health supported the study (R01DA021525, U01DA038886, R25DA037756). This research was undertaken, in part, thanks to funding from the Canada Research Chairs program through a Tier 1 Canada Research Chair in Inner City Medicine that supports Dr. Evan Wood. Dr. Milloy is supported in part by the National Institutes of Health (R01-DA021525) and the Michael Smith Foundation for Health Research. His institution has received unstructured funds from NG Biomed, Ltd., to support his research. The ELEVATE grant: Irish Research Council International Career Development Fellowship – co-funded by Marie Cure Actions (ELEVATEPD/2014/6); and the European Commission grant (701698) supports Dr. Klimas. Dr. Hayashi is supported by the Canadian Institutes of Health Research New Investigator Award (MSH-141971).

The funders had no role in the design and conduct of the study; the collection, analysis, and interpretation of the data; the preparation of the manuscript; or the decision to submit the manuscript for publication.

Conflict of interest

None reported.