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Health Psychol. Author manuscript; available in PMC 2017 March 01. Published in final edited form as: Health Psychol. 2016 March ; 35(3): 290–297. doi:10.1037/hea0000310.

Psychosocial factors in adherence to antiretroviral therapy among HIV-positive people who use drugs William K. Lee1, M. J. S. Milloy1, John Walsh2, Paul Nguyen1, Evan Wood1,3, and Thomas Kerr1,3 William K. Lee: [email protected]; M. J. S. Milloy: [email protected]; John Walsh: [email protected]; Paul Nguyen: [email protected]; Evan Wood: [email protected]

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1British

Columbia Centre for Excellence in HIV/AIDS, St. Paul's Hospital 608 - 1081 Burrard Street Vancouver BC, Canada V6Z 1Y6 2Department

of Educational Psychology and Leadership Studies, University of Victoria, PO Box 1700, STN CSC, Victoria, BC, Canada V8W 2Y2 3Department

of Medicine, University of British Columbia, 2775 Laurel Street, 10th Floor, Vancouver, BC, Canada V5Z 1M9

Abstract

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Objectives—Sub-optimal adherence to antiretroviral therapy (ART) among HIV-infected people who use illicit drugs (PWUD) remains a significant concern, and there is a lack of effective adherence interventions for this population. Therefore, we sought to identify psychosocial determinants of optimal adherence, including adherence self-efficacy and outcome expectancies, with the aim of informing interventions designed to improve adherence among PWUD. Methods—From December 2005 to November 2013, data were derived from the AIDS Care Cohort to evaluate Exposure to Survival Services (ACCESS), a prospective cohort of PWUD in Vancouver, Canada. Multivariable generalized estimating equations (GEE) analysis was used to identify longitudinal factors independently associated with ≥95% adherence to ART. Results—Among 667 participants, including 220 (33%) women, 391 (59%) had ≥95% ART adherence at baseline. In multivariable GEE analysis, adherence self-efficacy (Adjusted Odds Ratio [AOR] = 1.16, 95% Confidence Interval [CI]: 1.11 - 1.21 per 10-point increase) was independently and positively associated with adherence, while negative outcome expectancy (AOR = 0.95, 95% CI: 0.93 - 0.98) was negatively associated.

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Conclusions—In light of the ongoing challenges associated with ART adherence among HIVpositive PWUD, and our findings of associations between adherence, self-efficacy and outcomes expectancies, tailored intervention strategies based on constructs of social learning theory should be implemented and evaluated in an effort to improve adherence among HIV-infected PWUD.

Send correspondence to: Thomas Kerr, PhD, BC Centre for Excellence in HIV/AIDS, 608 - 1081 Burrard Street, Vancouver BC V6Z 1Y6, Canada, Phone: 604-806-9116, Fax: 604-806-9044, [email protected]. Author Contributions: The specific contributions of each author are as follows: WL, MJ, EW and TK were responsible for the research design; TK and JW designed the self-efficacy and outcome expectation measure; PN conducted the statistical analyses; WL prepared the first draft of the manuscript; All authors provided critical comments on the first draft of the manuscript and approved the final version to be submitted.

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Introduction

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The introduction of antiretroviral therapy (ART) has significantly impacted and altered the course of HIV disease (Hammer, 1996). Shown to reliably suppress levels of plasma HIV RNA, optimal treatment has led to large reductions in HIV-related morbidity and mortality (Hogg et al., 2001; Egger et al., 2002). In order to be fully effective and for long-lasting clinical success, an optimal level of adherence, commonly defined as participants who have received their ART ≥95% of the time, is required. It has been previously shown that this validated measure of adherence predicts virologic suppression and survival (Wood et al., 2003). On the other hand, non-adherence detrimentally affects virologic control, and subsequently, increases the risk of disease progression, as well as the transmission of HIV to others (Deeks, 2003; Montaner, 2011; Paterson et al., 2000). Further, sub-optimal levels of adherence increase the risk of viral mutations, which can lead to treatment failure and the transmission of drug-resistant virus to others (Tang, 2012). Despite the benefits of ART on survival and quality of life, a large body of research has shown that people who use illicit drugs (PWUD) often exhibit lower levels of adherence in comparison to individuals from other groups of people living with HIV (Bruce, & Altice, 2007; Wood, Montaner, Tyndall, Schechter, O'Shaughnessy, & Hogg, 2003). Previous studies have identified numerous factors that increase the risk of non-adherence among PWUD, including high-intensity drug use (Palepu, Tyndall, Yip, O'Shaughnessy, Hogg, & Montaner, 2003), co-morbid psychiatric disorders (Arnsten et al., 2007), as well as social and structural factors (e.g., incarceration and homelessness) (Tapp et al., 2011).

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One possible factor that may affect ART adherence is self-efficacy; that is, one's belief in their own ability to complete a certain task. This psychosocial concept, derived from Bandura's social learning theory (Bandura, 1977), has influenced the way clinicians and public health officials view and design health-related interventions (Bandura, 2001). Bandura posits that although heightened awareness and knowledge of health risks are important components for change, effective self-regulation and behavioral change also requires self-motivation and self-guidance. Further, a lack of a sense of self-efficacy can lead to discrepancies between knowledge and action-taking. As such, by enhancing individuals' perception of self-agency, one can exercise more control over their health, thus leading to better health outcomes. Results from past studies have supported the relationship between higher self-efficacy and higher adherence rates to health and medical regimens, including ART adherence (Bandura, 1990; Colbert, Sereika, & Erlen, 2013; Kerr, et al., 2004; Johnson et al., 2006; Trovato et al., 2012). However, these analyses have been limited to cross-sectional designs and the observed relationships have not been assessed longitudinally in community-derived samples of PWUD. Another psychosocial construct that has been examined in relation to ART adherence to treatment is outcome expectancies regarding ART (Reynolds et al., 2004), with past work suggesting a strong relationship between negative beliefs about ART and non-adherence (Kerr, et al., 2004). Given preliminary evidence suggesting that psychological constructs derived from social learning theory have been shown to be associated with adherence to different medical regimens, including ART among PWUD (Tyer-Viola, Corless, Webel, Reid, Sullivan, &

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Nichols, 2014), this study sought to build on this work by longitudinally assessing the relationships between adherence self-efficacy, outcome expectations, and adherence to ART among a community-recruited cohort of HIV-positive PWUD in Vancouver, Canada; a setting where all HIV/AIDS treatment and care is delivered at no-cost through the province's universal healthcare system. It is hypothesized that there would be a positive and independent association between adherence self-efficacy, and adherence to ART, whereas negative outcome expectations would yield a negative and independent association between adherence self-efficacy, and adherence to ART. Based on the adherence literature, although lower levels of self-efficacy and adherence have been observed among PWUDs compared to non-drug using populations (Sharpe et al., 2004), this study hypothesizes that these psychological constructs will predict adherence among PWUD in the same manner as nondrug using populations. Further, this study considers the role of self-efficacy, as it has been demonstrated to be a key construct in the development of interventions specifically tailored to not only PWUD, but also people living with HIV (Bandura, 1990; Bandura, 1999). Lastly, although several socio-demographic and behavioral variables (i.e., ethnicity, gender and drug-use patterns) have been shown in the literature to be associated with ART adherence (Golin, et al., 2002; Simoni et al., 1999; Sharpe et al., 2004), and therefore have been included as variables that might confound the relationship between self-efficacy and adherence.

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The AIDS Care Cohort to evaluate Exposure to Survival Services (ACCESS) is an observational prospective cohort of HIV-seropositive illicit drug users in Vancouver, Canada, and has been described in detail elsewhere (Strathdee, et al., 1998; Wood, et al., 2004). In brief, individuals were eligible for ACCESS if they were aged 18 years or older, HIV seropositive, used any illicit (injection or non-injection) drugs other than cannabis in the last month,and provided written informed consent. At baseline and semi-annually thereafter, participants answer a standardized interviewer administered questionnaire and provide blood samples for serologic analysis. To compensate participants for their time, participants received a stipend of $30 CDN at each study visit. This study has received approval from Providence Health Care/University of British Columbia's Research Ethics Board.

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The current study included individuals who had received ≥ 1 days of highly-active antiretroviral therapy (HAART) at the time of the baseline interview. Baseline HAARTnaïve individuals who initiated HAART during the study period were included from their next follow-up interview following initiation. The primary outcome of interest was ART adherence, defined as the number of days that ART was dispensed divided by the total number of days since a participant initiated HAART, capped at 180 days. This outcome was dichotomized as ≥95% vs.

Psychosocial factors in adherence to antiretroviral therapy among HIV-positive people who use drugs.

Suboptimal adherence to antiretroviral therapy (ART) among HIV-infected people who use illicit drugs (PWUD) remains a significant concern, and there i...
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