People who receive opioid substitution therapy to manage drug addiction are more likely to be on antiretroviral treatment and achieve an undetectable HIV viral load, according to study findings published in the journal AIDS.

“These findings are encouraging and support calls for greater integration of OAT [opioid agonist treatment] and HIV services as well as for interventions to reach people with HIV not on OAT to maximize the clinical and community benefits of antiretroviral therapy,” wrote study authors Stephen Juwono, Eugenia Socías, MD, and colleagues from the British Columbia Centre on Substance Use.

HIV is easily transmitted via shared drug injection equipment, and a substantial proportion of people who use drugs are living with HIV. But this population faces barriers that can make it difficult to start and stay on effective antiretroviral therapy and achieve viral suppression, including unstable schedules, stigma, poverty, homelessness and incarceration.

OAT, which uses medications such as methadone or buprenorphine to prevent withdrawal symptoms and ease cravings for heroin and other opioids, can help people reduce or stop substance use. OAT can lower the risk of overdose death and acquisition of HIV and hepatitis C; for those already living with HIV, OAT may improve engagement with care.

Juwono’s team assessed the impact of OAT on progression through the HIV cascade of care for people who use opioids in Vancouver. The cascade of care involves linkage to care, initiation of antiretroviral therapy, retention in care, ongoing adherence to treatment and, finally, achieving and maintaining an undetectable viral load, which prevents disease progression and HIV transmission.

After adjusting for other factors, people on OAT were nearly four times more likely to start antiretrovirals, about three times more likely to adhere to treatment and more than twice as likely to achieve viral suppression.

“This study found a high level of OAT engagement among people with HIV using unregulated opioids and that OAT engagement resulted in significantly increased progression through some of the higher steps of the HIV cascade,” wrote the study authors.