Full length articleMethadone maintenance therapy and viral suppression among HIV-infected opioid users: The impacts of crack and injection cocaine use
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)
Substance use and HIV disease progression in the HAART era: implications for the primary prevention of HIV
Life Sci.
(2011)Associations between use of crack cocaine and HIV-1 disease progression: research findings and implications for mother-to-infant transmission
Life Sci.
(2011)- et al.
Effects of early versus delayed initiation of antiretroviral treatment on clinical outcomes of HIV-1 infection: results from the phase 3 HPTN 052 randomised controlled trial
Lancet Infect. Dis.
(2014) - et al.
Cocaine use and risky injection and sexual behaviors
Drug Alcohol Depend.
(1995) - et al.
Patterns of heroin and cocaine injection and plasma HIV-1 RNA suppression among a long-term cohort of injection drug users
Drug Alcohol Depend.
(2012) - et al.
Incidence and determinants of initiation into cocaine injection and correlates of frequent cocaine injectors
Drug Alcohol Depend.
(2009) Substance abuse, adherence with antiretroviral therapy, and clinical outcomes among HIV-infected individuals
Life Sci.
(2011)- et al.
We need somewhere to smoke crack: an ethnographic study of an unsanctioned safer smoking room in Vancouver, Canada
Int. J. Drug Policy
(2015) - et al.
Antiretroviral adherence and HIV treatment outcomes among HIV/HCV co-infected injection drug users: the role of methadone maintenance therapy
Drug Alcohol Depend.
(2006) - et al.
The effect of persistence of cocaine use on 12-month outcomes for the treatment of heroin dependence
Drug Alcohol Depend.
(2006)