For people living with HIV (PLWH) adherence to antiretroviral therapy (ART) is crucial to achieve the desired treatment outcomes. One reason for nonadherence is HIV-related stigma,1–6 which encompasses experiences of prejudice, discrimination, or other negative attitudes because of one's HIV diagnosis.7–10 Some PLWH internalize stigma, accepting negative evaluations about having HIV as valid.6,7,11,12 Internalized stigma often predicts suboptimal ART adherence.6,7,12
How does internalized HIV-related stigma lead to ART nonadherence? The limited literature on mediating mechanisms explaining this association identified intrapersonal mechanisms such as depression,8,12,13 and interpersonal mechanisms such as attachment-related anxiety and loneliness7,12 as potential mediators.
An interpersonal mechanism associated with HIV-related stigma is the concern about being seen by others while taking HIV medication.7 HIV treatment is a challenging process, involving the need to take medication the same time each day and sometimes during inconvenient situations or in public settings. Thus, PLWH with such concerns may skip taking their medications in certain situations.2 This concern has been reported as a mediating variable in the association between internalized stigma and medication nonadherence.7
An intrapersonal mechanism that has gained attention in relation to ART adherence is treatment adherence self-efficacy.14,15 Self-efficacy is an individual's confidence in his or her ability to carry out a certain behavior or complete a task.16 HIV treatment self-efficacy refers to one's confidence in his or her ability to adhere to a treatment plan despite obstacles.14 Although adherence self-efficacy has been shown to predict optimal ART adherence,14,15,17,18 only 1 study, to our knowledge, has found an inverse association between internalized HIV stigma and adherence self-efficacy.19
Only 1 study examined adherence self-efficacy as a mediator in the stigma–adherence association.20 However, the self-efficacy measure in that study asked participants questions that are usually used when assessing adherence, such as “I can always follow my HIV medication schedule,” which may have inflated the association between self-efficacy and adherence. Additionally, experienced stigma rather than internalized stigma was assessed, and according to recent theoretical approaches and empirical data, internalized stigma is a better unique predictor of adherence, because stigma may have to be internalized to affect a person's behavior.6,21,22
In this study, we examined whether adherence self-efficacy is associated with a widely used measure of internalized stigma and mediates the association between internalized stigma and adherence. Given that previous research has found both interpersonal and intrapersonal mechanisms to be involved in the association between internalized stigma and medication adherence, we also aimed to examine the independent unique mediating roles (ie, parallel mediation) of concern about being seen taking HIV medication (an interpersonal mechanism) and adherence self-efficacy (an intrapersonal mechanism) in the stigma–adherence association, where both mechanisms were entered as mediators simultaneously. Examining simultaneous parallel mediation effects is important because it may be the case that 2 variables are significant mediators in 2 separate mediation analyses, but when entered simultaneously, one (or both) may fail to be a significant unique mediator (above and beyond the other mediating path) because of overlap in the mediation effects.23–25 Ajzen and Fishbein26 provided support for their hypothesis that interpersonal and intrapersonal factors contribute independently to the prediction of behavior (also see Mickelson and Williams27 for a dual-pathway theory of interpersonal and intrapersonal mechanisms in the association between poverty stigma and depression). Using simultaneous entry, one can also compare the 2 specific indirect effects to see if the mediating effect of one is stronger than the other.
We used the same sample (and the data on adherence, stigma, and concern about being seen taking HIV medication) used in our previously reported work7 on the mediating role of concern about being seen taking HIV medication in the stigma–adherence association. The current analyses take this program of research a step further by investigating the mediating effect of self-efficacy, as well as by examining simultaneous roles of these interpersonal and intrapersonal mechanisms in the relationship between stigma and medication adherence in an attempt to tease apart the independent mediating roles of these variables. This, in turn, may allow us to better understand the complex factors affecting treatment outcomes for PLWH, with the goal of developing more effective ART adherence interventions.
Participants and Procedures
Patients from an HIV clinic in Birmingham, AL gave written informed consent to participate in this institutional review board approved study between March 2013 and January 2015. Exclusion criteria included not being prescribed ART and/or being a current substance user. In the present analyses, 180 participants with data on the primary study variables were included. Time on ART and daily frequency of prescribed HIV medications (single pill once daily versus more complex regimens) was extracted from medical records. Participants self-reported their socioeconomic status.
Medication adherence was assessed using a single-item where participants reported their ability to take all HIV medication prescribed using a 6-point rating scale ranging from 1 (very poor) to 6 (excellent). Literature suggests this is a valid adherence measure associated with viral suppression.28,29 The scores were not normally distributed: 128 participants reported excellent adherence and 52 participants reported less than excellent adherence; therefore, this measure was dichotomized: Excellent adherence (1) or less than excellent adherence (0).
Internalized stigma was assessed using the revised 7-item Negative Self-Image subscale of the HIV Stigma Scale.11,30 A sample item is: “Having HIV in my body is disgusting to me.” Participants rated items using a Likert-type scale ranging from strongly disagree to strongly agree (Cronbach's α = 0.85 in this study).
Concern About Being Seen by Others While Taking HIV Medication
Two items from 2 separate measures were used. Item 1: “I don't want people to see me take my HIV medicines” (rated using a Likert-type scale from 1 to 5) was taken from the Patient Medication Adherence Questionnaire Version 1.0 (PMAQ-V1.0)31, and item 2: “Did not want others to notice you taking medication” (rated using a Likert-type scale from 1 to 4) was taken from the Adult AIDS Clinical Trial Group Adherence to Combination Therapy (AACTG) Questionnaire.32 After standardizing, the mean of the responses to both items was used in analyses.
The HIV Treatment Adherence Self-Efficacy Scale14 consists of 12 items with the stem: “How confident do you feel that you can do these things related to HIV?” Participants used a rating scale ranging from 1 (cannot do it all) to 10 (certain can do it). An example item is: “Stick to your treatment schedule even when your daily routine is disrupted.” In the current data, Cronbach's α was 0.94.
Age, race, gender, socioeconomic status, and duration of ART were entered as covariates in all analyses (using α = 0.05). Because preliminary analyses did not reveal significant associations between daily frequency of prescribed HIV medication and the main study variables (ie, internalized stigma, self-efficacy, concern about being seen by others while taking HIV medication, and medication adherence), analyses did not include daily frequency of medication as a covariate. (Results were similar, and conclusions the same when this variable was used as a covariate.) Multiple regression was used to assess the association between internalized stigma and self-efficacy. Logistic regression was used to examine the association between self-efficacy and medication adherence (a dichotomous outcome), with internalized stigma included or excluded from the analyses. To test for the mediating role of self-efficacy in the relationship between internalized stigma and medication adherence, we calculated bias-corrected 95% confidence intervals for indirect effects using bootstrapping with Process.33 To test for parallel mediation of concern about being seen taking HIV medication and self-efficacy in the relationship between internalized stigma and medication adherence, we also used Process to calculate simultaneous (specific) indirect effects. Sensitivity analyses evaluated ART adherence based on raw (continuous) scores rather than dichotomized adherence using bootstrapping (with no assumptions about distributions) in linear regression and mediation analyses.
Of the 180 participants, 62% were black and 64% were men, with an average age of 45.37 years (SD = 10.96); 35% were on a single pill once daily. In a regression analysis, internalized stigma was significantly associated with lower self-efficacy (B = −0.43, t = −2.82, P = 0.005). When entered into a logistic regression together with the covariates, self-efficacy was associated with a higher likelihood of excellent medication adherence [adjusted odds ratio (AOR) = 1.62, P = 0.001, 95% CI: (1.23 to 2.14)]. When self-efficacy and internalized stigma were entered simultaneously, self-efficacy remained significantly associated with excellent medication adherence; AOR = 1.56, P = 0.001, 95% CI: (1.19, 2.04), whereas the effect of internalized stigma was no longer significant [AOR = 0.61, P = 0.09, 95% CI: (0.34, 1.08)]. Mediation analysis revealed a significant indirect effect of internalized stigma on nonoptimal adherence through the pathway of lower self-efficacy [B = −0.17, SE = 0.14, 95% CI: (−0.53, −0.02); Fig. 1].
When entered simultaneously into a mediation analysis, both concern about being seen taking HIV medication and adherence self-efficacy had significant parallel mediating effects on the association between internalized stigma and medication adherence [B = −0.16, SE = 0.13, 95% CI: (−0.48, −0.01) and B = −0.41, SE = 0.23, 95% CI: (−0.88, −0.02), respectively for self-efficacy and concern about being seen taking HIV medication]. Paths in this model are presented in Figure 2. Internalized stigma was associated with both lower self-efficacy and increased concerns about being seen taking HIV medication, and both mediators were associated with suboptimal ART adherence in paths that are independent of each other. When the 2 mediations were accounted for, the remaining direct effect (which also includes indirect effects through variables not measured in this study) was reduced to almost zero (B = −0.09, P = 0.80; which was significant without the 2 mediators in the model: B = −0.62, P = 0.02). Contrast analysis did not reveal a significant difference in the size of the 2 mediating paths [B = 0.25, SE = 0.27, CI: (−0.26, 0.81)]. Sensitivity analyses using medication adherence as a continuous dependent variable yielded very similar results (see Supplemental Digital Content 1, http://links.lww.com/QAI/A916).
Results suggest that PLWH who internalize HIV-related stigma have decreased confidence in their ability to adhere to their treatment regimen when faced with challenges, which in turn decreases medication adherence. Thus, low adherence self-efficacy seems to be one mechanism by which internalized stigma affects medication adherence. In contrast, PLWH with low internalized stigma may tend to persevere and overcome obstacles to adhere to their treatment regimen.
We also found that adherence self-efficacy and concern about being seen taking HIV medication both mediate the association between internalized stigma and ART adherence in paths independent of each other. Moreover, these 2 factors accounted for nearly all the observed association between internalized stigma and ART adherence. Findings outline the vital importance of independent roles of both interpersonal (concern about being seen) and intrapersonal (adherence self-efficacy) mechanisms in explaining the effects of internalized HIV stigma on ART adherence.
Katz et al5 maintain that HIV-related stigma reduction interventions should target multiple levels of influence including both interpersonal and intrapersonal factors to achieve maximum effectiveness. This view coincides with present results that demonstrate the importance of both interpersonal and intrapersonal factors in undermining ART adherence. Adherence interventions may be successful by either targeting stigma in the community, reducing internalized stigma, building self-efficacy, or addressing interpersonal concerns, or if resources permit, by targeting all these factors simultaneously. Targeting a mediating construct will be effective to the degree that it explains the association between stigma and adherence. Targeting multiple mediators simultaneously may increase the effect of the intervention, provided that these factors have significant specific indirect effects independent of each other. Another intervention strategy is to find ways to block the paths from internalized stigma to self-efficacy or to interpersonal concerns, or to block the paths from low self-efficacy and from interpersonal concerns to nonadherence.
This study had limitations. We used self-report measures, which have known disadvantages. Mediation analyses are exploratory and causal inferences cannot be made because our study was cross-sectional. Furthermore, in mediation analysis there may be unobserved variables associated with both the mediators and the outcome, biasing results. Future research should replicate these findings using longitudinal designs and/or using nonquestionnaire measures, such as the experience sampling method, which has started to be used in HIV research.15
The present study is the first to demonstrate parallel mediation of both interpersonal and intrapersonal factors in the stigma–ART adherence association and highlights the importance of addressing both types of factors in understanding this association as well as for interventions.
The authors thank C. Blake Helms, Maria Lechtreck, Wesley Browning, Christy Thai, and all the research assistants for their help in data collection.
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