Impact of Opioid Substitution Therapy on Antiretroviral Therapy Outcomes: A Systematic Review and Meta-Analysis

Abstract

Background: Human immunodeficiency virus (HIV)-infected people who inject drugs (PWID) frequently encounter barriers accessing and remaining on antiretroviral therapy (ART). Some studies have suggested that opioid substitution therapy (OST) could facilitate PWID's engagement with HIV services. We conducted a systematic review and meta-analysis to evaluate the impact of concurrent OST use on ART-related outcomes among HIV-infected PWID.

Methods: We searched Medline, PsycInfo, Embase, Global Health, Cochrane, Web of Science, and Social Policy and Practice databases for studies between 1996 to November 2014 documenting the impact of OST, compared to no OST, on ART outcomes. Outcomes considered were coverage and recruitment onto ART, adherence, viral suppression, attrition from ART, and mortality. Meta-analyses were conducted using random-effects modeling, and heterogeneity assessed using Cochran Q test and I(2) statistic.

Results: We identified 4685 articles, and 32 studies conducted in North America, Europe, Indonesia, and China were included. OST was associated with a 69% increase in recruitment onto ART (hazard ratio [HR], 1.69; 95% confidence interval [CI], 1.32-2.15), a 54% increase in ART coverage (odds ratio [OR], 1.54; 95% CI, 1.17-2.03), a 2-fold increase in adherence (OR, 2.14; 95% CI, 1.41-3.26), and a 23% decrease in the odds of attrition (OR, 0.77; 95% CI, .63-.95). OST was associated with a 45% increase in odds of viral suppression (OR, 1.45; 95% CI, 1.21-1.73), but there was limited evidence from 6 studies for OST decreasing mortality for PWID on ART (HR, 0.91; 95% CI, .65-1.25).

Conclusions: These findings support the use of OST, and its integration with HIV services, to improve the HIV treatment and care continuum among HIV-infected PWID.

Keywords: HIV; antiretroviral treatment (ART); medication-assisted therapy for opioid dependence (MAT); people who inject drugs (PWID); systematic review.

Figure 1.

Forest plot of the effect of opioid substitution therapy on coverage of antiretroviral therapy (ART) among people who inject drugs (PWID), defined as the proportion of PWID on ART at a given time point. I² and P value are measures of between-study heterogeneity. Abbreviations: CI, confidence interval; N, total sample size of PWID; OR, odds ratio.

Figure 2.

Forest plot of the effect of opioid substitution therapy on adherence to antiretroviral therapy (ART) among people who inject drugs (PWID), defined as the proportion achieving a defined threshold of ART adherence, whether self-reported or objectively measured. I² and P value are measures of between-study heterogeneity. Abbreviations: CI, confidence interval; measure, method of measurement of adherence; N, total sample size of PWID; OR, odds ratio; threshold, percentage of doses taken to indicate adherence.

Figure 3.

Forest plot of the effect of opioid substitution therapy on plasma viral suppression among people who inject drugs (PWID) on antiretroviral therapy (ART), defined as the proportion of those on ART with undetectable plasma human immunodeficiency virus (HIV) RNA loads, based on the threshold of detection in each study (<500, <400 or <50 copies/mL). I² and P value are measures of between-study heterogeneity. Note that Roux used multiple thresholds depending on clinical site. Abbreviations: CI, confidence interval; N, total sample size of PWID; OR, odds ratio; threshold, number of HIV-1 RNA copies/mL used as threshold for HIV-1 RNA detection in that study.

Figure 4.

Forest plot of the effect of opioid substitution therapy on antiretroviral therapy (ART) discontinuation or attrition among people who inject drugs (PWID), defined as the proportion of those on ART who were lost to follow-up or discontinued ART during follow-up. I² and P value are measures of between-study heterogeneity. Abbreviations: CI, confidence interval; N, total sample size of PWID; OR, odds ratio; time on ART, average time on ART for study participants.