Elsevier

Drug and Alcohol Dependence

Volume 168, 1 November 2016, Pages 211-218
Drug and Alcohol Dependence

Full length article
Methadone maintenance therapy and viral suppression among HIV-infected opioid users: The impacts of crack and injection cocaine use

https://doi.org/10.1016/j.drugalcdep.2016.09.013Get rights and content

Highlights

  • The effect of methadone maintenance therapy (MMT) on viral suppression varied according to distinct patterns of cocaine use.

  • MMT was associated with increased odds of viral suppression among less than daily cocaine injectors.

  • Daily cocaine injectors did not experience the beneficial impact of MMT on viral suppression.

  • MMT was associated with increased odds of viral suppression regardless of crack cocaine use.

Abstract

Background

Methadone maintenance therapy (MMT) is associated with improved HIV treatment outcomes among people who use drugs (PWUD). The extent to which these benefits are sustained in the context of ongoing cocaine use is unclear. We assessed differential impacts of MMT on HIV viral load (VL) suppression in relation to discrete patterns of cocaine use.

Methods

Data was drawn from ACCESS, a prospective cohort of HIV-positive PWUD in Vancouver, Canada. Generalized linear mixed-effects were used to model the independent effect of MMT on VL suppression across strata of frequency of cocaine injection and crack smoking (≥daily versus <daily), after adjustment for confounders.

Results

The analysis included 397 HIV-positive opioid users who completed ≥1 study interview between 2005 and 2014. At baseline, 304 (77%) reported participation in MMT, 37 (9%) ≥daily cocaine injection, and 158 (40%) ≥daily crack smoking. In adjusted analyses, MMT remained independently associated with increased odds of VL suppression in both strata of crack smokers (AOR = 3.11, 95% CI: 1.86–5.21 and AOR = 1.48, 95%CI: 1.04–2.09, for ≥daily and <daily smokers, respectively), and among <daily cocaine injectors (AOR = 1.88, 95%CI 1.38–2.56), but not among ≥daily cocaine injectors (AOR = 1.37, 95%CI 0.53–3.49). Longer retention on MMT was positively associated with VL suppression in all strata of cocaine injection and crack smoke.

Conclusions

Exposure to MMT was associated with increased odds of VL suppression among HIV- positive opioid users regardless of crack use. However, this beneficial effect of MMT was lost among frequent cocaine injectors with shorter retention on MMT.

Introduction

The use of antiretroviral therapy (ART) in the control of the HIV pandemic is now firmly established (Joint United Nations Programme on HIV/AIDS, 2014). High quality evidence indicates that prompt initiation of ART is associated with reduced mortality and morbidity, and secondarily with reduced HIV transmission (Cohen et al., 2011, Grinsztejn et al., 2014, Insight Start Study Group et al., 2015, Rodger et al., 2014, Temprano Anrs Study Group et al., 2015. As such, guidelines for both high-income and resource-limited settings now recommend initiating ART immediately following diagnosis of HIV infection regardless of CD4 cell count (Panel on Antiretroviral Guidelines for Adults and Adolescents, 2015, World Health Organization, 2016).

Unfortunately, not all people living with HIV/AIDS PLWH have benefited equally from advancements in HIV/AIDS treatment. In particular, research shows that people who use drugs (PWUD) experience lower rates of access to ART, with consequent sub-optimal virological, clinical and transmission outcomes (Kamarulzaman and Altice, 2015, Milloy et al., 2012). Co-morbid mental illnesses, ongoing substance use, as well as social-structural factors, such as stigma, unstable housing, and criminalization, have been identified as factors compromising PWUD’s engagement in HIV care (Kamarulzaman and Altice, 2015, Milloy et al., 2012).

Despite these challenges, recent studies have documented improved HIV-related outcomes among opioid-dependent individuals enrolled in opioid substitution treatment (OST) programs, including increased access to and adherence to ART, and decreased HIV incidence (Ahamad et al., 2015, Altice et al., 2011, Lappalainen et al., 2015, Nosyk et al., 2015a, Palepu et al., 2006, Wood et al., 2005). While the potential of OST as a platform to facilitate engagement of PWUD in HIV care is encouraging, the extent to which these benefits are sustained in the context of ongoing cocaine use is unclear. This is particularly relevant for a number of reasons. First, there is substantial evidence of the deleterious impact of cocaine use on adherence to ART and some data describing hastened HIV disease progression among active cocaine users (Carrico, 2011). Second, cocaine use is highly prevalent among opioid-dependent individuals entering OST (Gonzalez et al., 2013, Sullivan et al., 2011). And third, there are no effective pharmacotherapies for the treatment of cocaine use disorders (Shorter et al., 2015)

Thus, given the critical role of sustained viral suppression in maximizing the individual- and population-level benefits of ART, the aim of this study was to evaluate whether the effect of methadone maintenance treatment (MMT) on viral suppression differs among opioid users with distinct patterns of cocaine use. We were interested in investigating not only the impacts of high intensity cocaine use (i.e., ≥daily use), but also on potential differences between routes of administration (i.e., crack smoking and cocaine injection).

Section snippets

Study design and population

Data for this study were drawn from the AIDS Care Cohort to evaluate Exposure to Survival Services (ACCESS), an ongoing prospective cohort of HIV-positive adults who use illicit drugs in Vancouver, Canada that began recruitment in 2005. Eligibility criteria include HIV-seropositivity, age  18 years, residency within greater Vancouver, and having used illicit drugs other than cannabis in the previous month. Participants are recruited through snowball sampling and extensive street outreach with a

Results

Between December 2005 and May 2014, 847 individuals were enrolled in the ACCESS cohort. Among the 434 self-reported opioid users recruited, 397 met the eligibility criteria, and were thus included in the present analysis. Baseline characteristics of study participants stratified by enrollment in a MMT program at baseline are presented in Table 1. The median age of the study sample was 41 (Interquartile range [IQR] 36–47), and 234 (59%) were male. At baseline, 304 (77%) reported being enrolled

Discussion

In this longitudinal study of HIV-positive opioid users, we found that the effect of MMT on VL suppression differed in relation to distinct patterns of cocaine use. Specifically, while enrollment in a MMT program was associated with increased odds of VL suppression among less than daily cocaine injectors, this beneficial effect of MMT was lost among more frequent cocaine injectors. However, for frequent cocaine injectors who were retained on MMT for longer consecutive periods a positive impact

Author’s contribution

MES, EW and MJM designed the study. HD conducted the statistical analysis. MES wrote the first draft of the manuscript. All authors contributed to the interpretation of the results, provided critical revisions to the article, and read and approved the final version of the manuscript.

Funding

The study is supported by the US National Institutes of Health (R01-DA021525) and the Canadian Institutes of Health Research (MOP-79297 and RAA-79918). This research was undertaken, in part, thanks to funding from the Canada Research Chairs program through a Tier 1 Canada Research Chair in Inner City Medicine, which supports EW. MJM is supported in part by the US National Institutes of Health (R01-DA021525). MES is supported by Michael Smith Foundation for Health Research post-doctoral

Conflict of interest

The authors declare no conflict of interest. The University of British Columbia has received unstructured funding from NG Biomed, Ltd., to support MJM’s research. JM has received limited unrestricted funding, paid to his institution, from Abbvie, Bristol-Myers Squibb, Gilead Sciences, Janssen, Merck and ViiV Healthcare.

Acknowledgements

The authors thank the study participants for their contributions to the research, as well as current and past researchers and staff. We would specifically like to thank: Kristie Starr, Deborah Graham, Tricia Collingham, Carmen Rock, Jennifer Matthews, Steve Kain, Benita Yip and Guillaume Colley for their research and administrative assistance.

References (50)

  • K. Ahamad et al.

    Effect of low-threshold methadone maintenance therapy for people who inject drugs on HIV incidence in Vancouver, BC, Canada: an observational cohort study

    Lancet HIV

    (2015)
  • F.L. Altice et al.

    HIV treatment outcomes among HIV-infected, opioid-dependent patients receiving buprenorphine/naloxone treatment within HIV clinical care settings: results from a multisite study

    J. Acquir. Immune Defic. Syndr.

    (2011)
  • P. Azar et al.

    Drug use patterns associated with risk of non-adherence to antiretroviral therapy among HIV-positive illicit drug users in a Canadian setting: a longitudinal analysis

    BMC Infect. Dis.

    (2015)
  • M.K. Baum et al.

    Crack-cocaine use accelerates HIV disease progression in a cohort of HIV-positive drug users

    J. Acquir. Immune Defic. Syndr.

    (2009)
  • M.S. Cohen et al.

    Prevention of HIV-1 infection with early antiretroviral therapy

    N. Engl J. Med.

    (2011)
  • J. De Irala et al.

    Reliability of self-reported human immunodeficiency virus risk behaviors in a residential drug treatment population

    Am. J. Epidemiol.

    (1996)
  • K. DeBeck et al.

    Smoking of crack cocaine as a risk factor for HIV infection among people who use injection drugs

    CMAJ

    (2009)
  • K. DeBeck et al.

    Public crack cocaine smoking and willingness to use a supervised inhalation facility: implications for street disorder

    Subst. Abuse Treat. Prev. Policy

    (2011)
  • N.S. Farronato et al.

    A systematic review comparing cognitive-behavioral therapy and contingency management for cocaine dependence

    J. Addict. Dis.

    (2013)
  • B. Fischer et al.

    Crack across Canada: comparing crack users and crack non-users in a Canadian multi-city cohort of illicit opioid users

    Addiction

    (2006)
  • B. Fischer et al.

    Hepatitis C virus transmission among oral crack users: viral detection on crack paraphernalia

    Eur. J. Gastroenterol. Hepatol.

    (2008)
  • A. Gonzalez et al.

    Substance use predictors of poor medication adherence: the role of substance use coping among HIV-infected patients in opioid dependence treatment

    AIDS Behav.

    (2013)
  • D.W. Hosmer et al.

    Confidence interval estimation of interaction

    Epidemiology

    (1992)
  • Insight Start Study Group et al.

    Initiation of antiretroviral therapy in early asymptomatic HIV Infection

    N. Engl. J. Med.

    (2015)
  • Joint United Nations Programme on HIV/AIDS

    90-90-90 An Ambitious Treatment Target To Help End The AIDS Epidemic

    (2014)
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