Medication beliefs as mediators of the health literacy-antiretroviral adherence relationship in HIV-infected individuals.

Identifying modifiable barriers to antiretroviral adherence remains an important aim. We hypothesized that mistaken beliefs regarding taking HIV medications mediated the relation between low literacy and poor adherence. We studied 87 HIV-infected individuals on standard antiretroviral regimens for >or= 3 months. Adherence was assessed using pharmacy refill records. Medication beliefs, including an individual's norm for acceptable adherence, were measured using questions developed by expert panel. Literacy was associated with >or=95% adherence (64% for >or=9th grade level vs. 40% for <9th grade level). Participants with <95% adherence had a lower threshold of acceptable adherence than those with >or=95% adherence [80% adherence (interquartile range 70-90%) vs. 90% adherence (interquartile range 80-90%)]. However, the effect was independent of literacy. No other beliefs assessed were associated with adherence. Although the beliefs assessed do not mediate the relation between literacy and adherence, we identified low adherence norms as a potentially modifiable belief associated with adherence.