This study is based on a large and diverse sample of subjects enrolled in ART programs in Viet Nam, and indicates that suboptimal ART adherence is a critical issue that requires attention. Using the VAS measurement, we found that one in four (24.9%) people taking ART were not optimally adherent over the preceding month, and a higher proportion (29.1%) were classified as non-adherent with the AACTG measure of 4-day on-time medication use. These two prevalence estimates are higher than both prior studies in Viet Nam [4, 5]. Compared with other published studies from East and South Asia, the suboptimal adherence we report is at the high end of the range (from 0.4% to 26.0%).
Direct comparison of suboptimal ART adherence prevalence from various studies is hindered by differences in study design and adherence measures, including time reference periods. Face-to-face interviews may be unreliable because patients may not be honest about their suboptimal adherence when they are interviewed by clinic staff about this sensitive issue. To our knowledge, the present study is the first to use the ACASI technique to investigate ART adherence in a developing country. This approach is widely used in other contexts to reduce social desirability response bias and enhance the veracity of self-report [6, 9]. In Viet Nam, this technique has been useful to enhance disclosure of sensitive information in analyses with adolescents and injection drug users . The improved privacy and confidentiality of the ACASI method may explain the relatively high estimates of suboptimal adherence we report here.
This study extends previous analyses of the determinants of ART suboptimal adherence that have been conducted in Asia and other regions in the world, and has clear implications for care for PLHIV in low resource environments. Among the many variables examined, depressive symptoms had one of the strongest associations with suboptimal adherence. This is consistent with research from high-income countries and in Africa [29–33] and strengthens the argument for mental health services that may improve ART adherence outcomes [33–36]. Currently, mental health services are not available at most HIV outpatient clinics in Viet Nam .
This study also confirmed that heavy alcohol use is a significant predictor of suboptimal ART adherence. Globally, alcohol use has been recognized as a major barrier for medication adherence . A meta-analysis reported that among PLHIV, those who drink alcohol were approximately 40–50% less likely to be adherent compared with those who abstain or drink relatively little, and the effect size was even greater for problem drinkers . The present study found that recent illicit drug use was not itself associated with suboptimal ART adherence, but we identified a significant interaction with recent heavy alcohol use. Compared with subjects with recent heavy alcohol use alone, ART adherence was much poorer among subjects who reported heavy alcohol use and illicit drug use. A number of interventions currently exist in Viet Nam to support drug users, including methadone maintenance therapy, needle and syringe exchange, condom distribution, and peer support groups. However, little effort has been directed to support alcohol abusers, including alcohol abusers living with HIV/AIDS. An important implication of our findings is that care and support for people who use alcohol and/or illicit drugs should be enhanced and sustained in Viet Nam, as a core part of comprehensive efforts to improve HIV treatment adherence. These efforts should be conducted in parallel with research, because few systematic evaluations have assessed the effectiveness of programs designed to optimize ART adherence for substance users, especially in resource-limited settings .
Another psychological factor identified was the fatalistic belief that chance or luck controls one’s destiny, including health outcomes. The multivariate results indicated that after adjusting for other variables, chance health locus of control remained a significant predictor of suboptimal ART adherence. This finding may be used to guide HIV clinic counsellors to discuss fatalistic beliefs as a barrier to self-care and healthy behaviours. Consistent with other research of the influence of patient-provider relationships on ART adherence [39, 40], this study found that the perceived quality of information from health care providers was positively associated with adherence.
An interesting insight emerged from the analysis of how family and social support influence adherence. With a relatively large sample size, this study had enough statistical power to examine the relative importance of different types of social and family support in a multivariable model. We did not find significant relationships between ART adherence and different types of support from family, peers and social organisations. Both patient overall satisfaction with support received, and feelings of social connectedness, significantly correlated with adherence. In developing countries, a sense of social responsibility may influence patient adherence . Specific interventions to enhance a sense of connectedness that maintains and strengthens social responsibility among patients, their families, and peers may help to optimize ART adherence.
The present study has some limitations. Selection bias may have occurred, because only patients on ART treatment who came to a clinic at the time of data collection and provided informed consent were included. This excluded patients who were not retained in HIV care, patients who missed clinical appointments during the study period, or patients who refused to participate in the study. Although the number of patients studied per clinic was proportional to the number of patients registered and receiving ART in each site, and researchers made considerable efforts to revisit these clinics several times to recruit patients, it is conceivable the non-participants were at higher risk of poor adherence. Therefore, the current study may underestimate the true level of suboptimal ART adherence. A further limitation is the cross-sectional nature of this study, which limits the ability of the analysis to determine the direction of causation.