People with opioid use disorder who received methadone were less likely to discontinue treatment compared with those who received buprenorphine/naloxone, according to a new study involving UBC faculty of medicine researchers.
The study, published this week in JAMA, evaluated the risk of treatment discontinuation and mortality in people prescribed opioid agonist treatment (OAT) in British Columbia over a 10-year period.
“The benefits of these medications are only realized while people are using them. However, retention in OAT has steadily declined over the past 13 years,” said study co-author Dr. Paxton Bach, clinical assistant professor in UBC’s department of medicine and co-medical director for the BC Centre on Substance Use (BCCSU). “Continuous evaluation and refinement of clinical guidance based on the strongest available evidence is vital in order to provide the best possible support to people with opioid use disorder in B.C. and around the world.”
The study was a collaboration between scientists and public health professionals from the Centre for Advancing Health Outcomes, UBC, Simon Fraser University, BCCSU and McGill University in Canada, and universities and institutions in the United Kingdom, Austria and across the United States.
Both buprenorphine/naloxone and methadone are available in B.C. for the treatment of opioid use disorder through specialized drug treatment centres and office-based clinical settings. The analysis included everyone in B.C. who received either medication from January 1, 2010 to March 17, 2020 (30,891 people) and compared the impact on retention and all-cause mortality.
Fentanyl was first detected in the drug supply in 2012 and became the primary driver of overdose mortality in 2016. The study period ended the day before BC declared a public health emergency for COVID-19. Just over 61 per cent of people in the cohort were prescribed methadone.
Overall, the study found that people who received methadone had a 37–40 per cent lower rate of treatment discontinuation compared with those who received buprenorphine/naloxone. The risk of mortality was low during treatment and did not differ meaningfully between the two medications (0.13 per cent vs. 0.08 per cent). Importantly, the findings were consistent after the introduction of fentanyl and across patient subgroups, including youth under 24 years of age, people with severe mental disorders and people with concurrent chronic pain.
“Reducing the risk of treatment discontinuation saves lives. With thousands of lives lost since the introduction of fentanyl into B.C.’s unregulated drug supply, it is important that we continue to evaluate the best available treatment options,” said first author Dr. Bohdan Nosyk, scientist at the Centre for Advancing Health Outcomes and a professor in the Faculty of Health Sciences at Simon Fraser University. “Comparative studies like this using high-quality health administrative data are one of the best sources of evidence we have to evaluate how our treatment options are performing as the toxic drug supply continues to evolve.”
Earlier research shows that mortality risk for people on OAT more than doubles after treatment discontinuation versus while on treatment. According to the latest release from the B.C. Coroners Service, about six people per day die from unregulated drugs.
The researchers noted that while this evidence suggests that methadone remains the treatment option with the strong evidence of effectiveness, decisions about medication choice must be made in collaboration with patients. Developing novel therapeutic regimens, like co-prescription of hydromorphone, is also an urgent priority. Additionally, there needs to be consideration the existing barriers to treatment retention, like urine drug screening and daily witnessed doses, and incorporation of strategies to improve retention, like engagement of peer support workers.
Funding for this study was provided by the Health Canada Substance Use and Addictions Program and the National Institute on Drug Abuse of the National Institutes of Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of the funders.
The Centre for Advancing Health Outcomes and BCCSU are jointly affiliated with the UBC faculty of medicine, Providence Health Care and Providence Research. A version of this article originally appeared on the Centre for Advancing Health Outcomes website.