Does Initiation of Opioid Agonist Therapy Affect the Use of Other Substances?

Opioid agonist therapy (OAT) with methadone or buprenorphine reduces unhealthy opioid use and the harms associated with it. Its effect on the use of other substances is less clear. Researchers used data from 3 ongoing prospective cohort studies of people who use drugs in Vancouver, Canada to compare self-reported substance use trends before and after engaging in OAT. This analysis included 1107 participants who initiated OAT after study enrollment and had at least 1 study visit after initiation.

• For heroin and non-medical use of prescription opioids (NMUPO), there was a significant decrease in per-year increase in use trends post-OAT treatment initiation, compared with pre-treatment trends:
  • Heroin: adjusted odds ratio (aOR), 1.19 pre-treatment versus 0.80 post-treatment.
  • NMUPO: aOR, 1.04 pre-treatment versus 0.87 post-treatment.
• For benzodiazepines, there was a trend of declining use pre-treatment (per-year increase aOR, 0.84) that continued and strengthened post-treatment (aOR, 0.73).
• For daily alcohol use, there was a trend of declining use pre-treatment (per-year increase aOR, 0.91) that reversed post-treatment (aOR, 1.03).
• For stimulants and cannabis, there were no significant changes in post-treatment use trends, compared with pre-treatment use trends.

Comments: The focus on urine drug testing for individuals receiving OAT may lead providers to overlook unhealthy alcohol use. While the rates and changes in alcohol use were relatively modest, this study suggests that we need to pay more attention to this. It would be interesting to see if the effects of extended-release naltrexone are different in this respect.

Darius A. Rastegar, MD

Reference: Dong H, Hayashi K, Milloy MJ, et al. Changes in substance use in relation to opioid agonist therapy among people who use drugs in a Canadian setting. Drug Alcohol Depend. 2020;212:108005.