Factors linked to transitions in adherence to antiretroviral therapy among HIV-infected illicit drug users in a Canadian setting

Abstract

HIV-positive people who use illicit drugs typically achieve lower levels of adherence to antiretroviral therapy and experience higher rates of sub-optimal HIV/AIDS treatment outcomes. Given the dearth of longitudinal research into ART adherence dynamics, we sought to identify factors associated with transitioning into and out of optimal adherence to ART in a longitudinal study of HIV-infected people who use illicit drugs (PWUD) in a setting of universal no-cost HIV/AIDS treatment. Using data from a prospective cohort of community-recruited HIV-positive illicit drug users confidentially linked to comprehensive HIV/AIDS treatment records, we estimated longitudinal factors associated with losing or gaining ≥95% adherence in the previous six months using two generalized linear mixed-effects models. Among 703 HIV-infected ART-exposed PWUD, becoming non-adherent was associated with periods of homelessness (adjusted odds ratio [AOR] = 2.52, 95% confidence interval [95% CI]: 1.56–4.07), active injection drug use (AOR = 1.25, 95% CI: 1.01–1.56) and incarceration (AOR = 1.54, 95% CI: 1.10–2.17). Periods of sex work (AOR = 0.51, 95% CI: 0.34–0.75) and injection drug use (AOR = 0.62, 95% CI: 0.50–0.77) were barriers to becoming optimally adherent. Methadone maintenance therapy was associated with becoming optimally adherent (AOR = 1.87, 95% CI: 1.50–2.33) and was protective against becoming non-adherent (AOR = 0.52, 95% CI: 0.41–0.65). In conclusion, we identified several behavioural, social and structural factors that shape adherence patterns among PWUD. Our findings highlight the need to consider these contextual factors in interventions that support the effective delivery of ART to this population.

Keywords:

• antiretroviral therapy
• adherence
• drug users
• methadone
• incarceration
• sex work

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, Brandon Marshall, Caitlin Johnston, Steve Kain, Benita Yip and Guillaume Colley for their research and administrative assistance.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

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]. The funders had no role in the design and conduct of this study; collection, management, analysis and interpretation of the data; and preparation, review or approval of the manuscript. Dr Milloy is supported in part by the United States National Institutes of Health. This work was supported in part by a Tier 1 Canada Research Chair in Inner-City Medicine awarded to Dr Wood. Dr Montaner is supported by the British Columbia Ministry of Health and through an Avant-Garde Award (No. 1DP1DA026182) from the National Institute of Drug Abuse (NIDA), at the US National Institutes of Health (NIH). He has also received financial support from the International AIDS Society, United Nations AIDS Program, World Health Organization, National Institutes of Health Research-Office of AIDS Research, National Institute of Allergy & Infectious Diseases, The United States President's Emergency Plan for AIDS Relief (PEPfAR), UNICEF, the University of British Columbia, Simon Fraser University, Providence Health Care and Vancouver Coastal Health Authority.