Opioid substitution treatment (OST) increases the likelihood that addicts will take their HIV antiretrovirals (ARVs) as prescribed. To determine this, researchers in British Columbia, Canada, followed 1,852 HIV-positive injection drug users (IDUs) for a median five and a half years between 1996 and 2010.

While on OST, participants took ARVs 56 percent of the time; when not on OST, participants took ARVs 36 percent of the time. After accounting for various factors that may have influenced these rates, the researchers found that OST upped adherence by 68 percent.

The study's lead author, Bohdan Nosyk, PhD, a research scientist at the BC Centre for Excellence in HIV/AIDS and an associate professor at Simon Fraser University, attributes this beneficial effect of drug treatment to “the greater linkage to health care that comes with initiating OST, and also the stability that OST can provide to people with opioid dependence.”

Nosyk says that his study “demonstrates that comprehensive and integrated health care, incorporating addiction treatment in primary care, is clearly critical for the successful treatment of HIV-positive individuals who inject drugs.”