Opioid substitution therapy improves many ART-related outcomes among people who inject drugs

Opioid substitution therapy has a key roll in improving antiretroviral therapy (ART)-related outcomes among HIV-positive people who inject drugs, according to a systematic review and meta-analysis published in the online edition of Clinical Infectious Diseases. Opioid substitution therapy was associated with enhanced recruitment to treatment, better adherence and increased rates or viral suppression. Over 36,000 people were included in the analysis, but there were limited data from countries with severe HIV epidemics among people who inject drugs, such as Russia.

“This systematic review found strong evidence to support the use of OST [opioid substitution therapy] and its inclusion in routine HIV care for improving the treatment and care continuum amongst HIV-positive PWID [people who inject drugs],” write the authors. “It supports the need for policy and health system reforms to accelerate the integration of OST and HIV treatment services.”

Nearly a third of new HIV infections outside sub-Saharan Africa involve people who inject drugs. The epidemic in this population is rapidly expanding in Eastern Europe and Central Asia. Outbreaks of HIV among people who inject drugs have also been observed in high-prevalence settings, including Kenya and Tanzania.

People who inject drugs often have poor levels of engagement with HIV care and sub-optimal ART outcomes. Opioid substitution therapy services have the potential to boost uptake of ART and retention in care among drug users.

An international team of investigators pulled together the evidence concerning the impact of opioid substitution therapy on ART-related outcomes, including recruitment to treatment, adherence, viral suppression and CD4 cell count increase, stopping treatment and mortality.

Studies conducted between 1996 and 2014 reporting on these outcomes and involving adults living with HIV who inject drugs were eligible for inclusion. A total of 32 eligible studies involving approximately 36,000 people were identified. These studies were conducted in nine separate countries. The median duration of follow-up was 24 months.

Ten studies reported on ART coverage. Overall, opioid substitution therapy was associated with a 54% increase in the odds of being on ART (OR, 1.54; 95% CI, 1.17-2.03, p = 0.002).

ART initiation was reported in four studies, showing that opioid substitution therapy increased the chances of starting ART by 87% (HR = 1.87; 96% CI, 1.50-2.33, p < 0.001).

Five studies reported on adherence, with opioid substitution therapy associated with a two-fold increase in adherence (OR, 2.14; 95% CI, 1.41-3.26, p < 0.001).

Viral suppression was analysed in ten studies, their pooled data showing that use of opioid substitution therapy increased the odds of achieving suppression (viral low below 500, 400 or 50 copies/ml) by 45% (OR, 1.45; 95% CI, 1.21-1.73, p < 0.001).

There was only modest evidence that opioid substitution therapy had a positive impact on CD4 cell increases. However, longer duration of follow-up was associated with larger CD4 cell count increases while on opioid substitution therapy.

People receiving opioid substitution therapy were significantly less likely to discontinue ART. Data from the seven studies reporting on this outcome showed that treatment reduced the odds of stopping ART by 23% (p = 0.01).

Six studies reported on the impact of opioid substitution therapy on mortality risk. Overall, treatment reduced mortality risk by a non-significant 9%.

“We found strong evidence of a positive impact on most outcomes,” comment the authors.

However, they acknowledge that they had limited data from the several countries with especially severe epidemics of HIV among people who inject drugs, including Ukraine, Russia, Malaysia, USA and China.

Nevertheless, they conclude, “the review provides evidence for the multiple potential benefits of OST, and its pivotal importance in a combination approach to harm reduction.”