In a diverse sample of 224 men and women living with HIV in the Pacific Northwest, overall self-reported adherence to antiretroviral medications was moderate, declining over time from 73% to 59%. African Americans, in particular, reported lower adherence compared to white participants at 3 months, and older age was also associated with lower odds of adherence. The latter association appeared to be an artifact of there being more older African Americans in our sample. Indeed, while previous research has demonstrated that minority status is often associated with nonadherence, older age tends to be associated with higher rates of antiretroviral adherence.45
In addition, prevalence of AOD was high in the sample: one fourth of the sample met or exceeded the clinical threshold of the AUDIT, indicating a strong likelihood for hazardous or harmful alcohol consumption, while over half of the sample reported hard drug use.
Prospective analyses indicated that medication-specific social support moderated the association between both alcohol and hard drugs at baseline and adherence to antiretroviral medication three months later. Specifically, when alcohol problems increased from the lowest measured level to the clinical threshold, the probability of 100% medication adherence remained stable (75–77%) among individuals with high medication support. In contrast, the probability of 100% adherence decreased from 61% to 37% when medication support was low. Similarly, medication support buffered the effect of hard drug use on medication adherence. When weekly hard drug use increased from zero to 1 day the probability of 100% medication adherence among individuals with high medication support remained the same (74–78%). However, when medication support was low, the probability of 100% adherence decreased from 65% to 48%. Interestingly, there was no finding of a moderating role of general social support.
While these findings should be viewed as preliminary, they offer an explanation to the stubbornly inconsistent findings in the literature regarding associations between AOD use and antiretroviral adherence. Although there have been calls to investigate factors that might explain the inconsistencies, few researchers have systematically examined potential moderators of this relationship. Given the consistently positive association between social support and adherence and its applicability in interventions, social support was targeted as a moderator. Our findings showed that medication-specific but not general social support moderated the association between AOD use and adherence. Perhaps this is because general social support has been shown to promote well-being, while specific social support is tied to particular functions.46
Optimal adherence to antiretroviral medication requires fastidious attention to daily scheduling, the ability to plan ahead for possible disruptions, and forbearance in the face of treatment fatigue and environmental obstacles. Social support that specifically addresses medication adherence would more likely target these antecedents of adherence. Indeed, in a systematic review of the research literature on patient support and education interventions intended to improve adherence, findings showed that interventions targeting practical medication management skills were associated with improved adherence outcomes.47
Alternatively, another potential explanation for the differential findings for medication-specific versus general support is that the two measures assessed different dimensions of support: the general social support items tapped perceptions of available support while the medication-specific social support items assessed actual receipt of support. Future research might attempt to disentangle the specificity and type of support.
Our results suggest that even if PLWH use drugs or alcohol, there may be factors that help them achieve optimal adherence. Thus, if abstinence is an unrealistic goal (which seems likely among many of the chronic users among HIV populations), a harm reduction approach that stresses consistent adherence bolstered with support specifically targeted to medication taking even during times of AOD use might be adopted. Some have argued that this is not ideal, as at least with alcohol use, abstinence has been associated with better adherence compared with at-risk usage or moderate-usage.10
Nonetheless, our findings showed that there are protective factors (i.e., medication-specific social support) that may help individuals with their medication regimens when abstinence does not appear obtainable. This offers preliminary support for practice and policy guidelines for HIV treatment and care.
There may be intervention components beyond medication-specific social support that could help HIV-positive AOD users achieve better adherence. For example, a motivational interviewing and cognitive-behavioral intervention with PLWH who met criteria for hazardous drinking showed that while there were no significant intervention effects for alcohol use, participants showed improvement in adherence at 3 month follow-up.48
Supplemental education about interactions may also be helpful; while controlled intervention studies are largely not available, existing data suggest that interactions between medications commonly prescribed for patients with HIV and illicit drugs can occur, and health care professionals should encourage open dialogue with their patients on this issue.49
Enhancing social support services in general for HIV-positive AOD users, which may include promoting a stable routine and structure that also provides medication-specific support, is another type of intervention that may prove useful. Indeed, although studies have generally shown that adherence is lower among current drug users,14,21
other studies have found that HIV-positive drug users who have access to substance abuse and mental health treatment achieve similar levels of adherence as HIV-positive non-illicit drug users.14,50
Referrals and treatment for mental health problems may be particularly beneficial for this population as AOD is often associated with depression,51
a consistent barrier to adherence and HIV viral suppression.30,52
Finally, other studies have highlighted the importance of the patient-provider relationship and communication supports, especially social support and ancillary services, in increasing adherence among marginalized populations.14,37
Health care professionals may be a rich resource for providing patients with medication-specific social support. Provider education around these issues may thus be an important intervention component to ensure that opportunities to provide medication support are taken, created, and maintained.
Taken together, our results suggest the importance of medication-specific social support to treat comorbid HIV and AOD use. Indeed, researchers have called for multifaceted interventions that are able to address a matrix of factors to promote adherence.53,54
Medication-specific social support may be one such important factor.
Despite this optimistic view, however, findings only showed medication-specific social support moderating the AOD-adherence relationship at 3 months, but not at 6 or 9 months. Our post hoc analyses indicated that one possibility for this was a progressive drop in medication-specific social support at 6 and 9 months, which may have negated any benefit that initial elevations in medication social support would have afforded. Indeed, our results indicate that the conclusion of the peer intervention at 3 months may have accounted for this drop. Our findings are modest given that the moderation effects did not replicate at 6 or 9 months; however, the effect at 3 months was robust and consistent with respect to both measures of AOD. Clearly, these results need to be replicated to further clarify the role and impact of medication-specific social support. One possibility is that perhaps ongoing medication-specific social support needs to be developed in programs for HIV-positive alcohol and substance users in order to maintain adherence gains.
Given that the buffering effect was moderate in size and noted only at the 3-month assessment, our results should be considered preliminary, and there are certainly other important factors that impact adherence among AOD users, many of which may be beyond the scope of social support to buffer. Persons with heavy AOD use are at increased risk for homelessness, unemployment, and incarceration. Lack of stable housing and changes in routines affect ability to track dose intake and maintain adherence.55
For example, research has shown that alcohol reduced patient abilities to maintain a consistent pill-taking schedule.15
Another potential mechanism is that patients who use AOD may intentionally skip HAART doses because of beliefs about negative interactions between AOD and HAART.56
Indeed, a recent study demonstrated that beliefs that alcohol and HIV medications should not be mixed were common among PLWH, and that stopping antiretroviral therapy when drinking was associated with treatment nonadherence over and above problem drinking.57
Alternatively, it may be that AOD use results in cognitive impairments that make adherence more difficult.58–60
These factors need to be considered as well in any comprehensive adherence-promotion intervention. There were some methodological limitations to our investigation. First, our estimates of adherence relied solely on self-report, which is known to overestimate adherence and is subject to recall bias and social desirability.54
However, it is generally considered a valid assessment technique that correlates consistently (if moderately) with biological markers of treatment success such as viral load and CD4 count.61,62
Second, we only found the effects for one time point, suggesting the preliminary nature of our findings and the potential tenuousness of the effect. Finally, the effect sizes were moderate,63
suggesting that perhaps the inclusion of other moderating factors are needed to more fully explain the effects on adherence.
Indeed, future studies that examine potential moderators and mediators of the relation between AOD and adherence are crucial as they have important treatment implications for this high-risk and marginalized group. A few studies have begun to examine these relationships; for example, positive affect and self-efficacy have been shown to be associated with higher levels of adherence among drug users.33, 64
Our findings suggest that medication-specific social support may be another protective factor, potentially assisting with the development of innovative psychological treatments designed to meet the needs of HIV-positive AOD users.