Age-associated predictors of medication adherence in HIV-positive adults: health beliefs, self-efficacy, and neurocognitive status.

OBJECTIVE: Although most agree that poor adherence to antiretrovirals is a common problem, relatively few factors have been shown to consistently predict treatment failure. In this study, a theoretical framework encompassing demographic characteristics, health beliefs/attitudes, treatment self-efficacy, and neurocognitive status was examined in relationship to highly active antiretroviral therapy adherence. DESIGN: Prospective, cross-sectional observational design. MAIN OUTCOME MEASURES: Neuropsychological test performance, health beliefs and attitudes, and medication adherence tracked over a 1-month period using electronic monitoring technology (Medication Event Monitoring System caps). RESULTS: The rate of poor adherence was twice as high among younger participants than with older participants (68% and 33%, respectively). Results of binary logistic regression revealed that low self-efficacy and lack of perceived treatment utility predicted poor adherence among younger individuals, whereas decreased levels of neurocognitive functioning remained the sole predictor of poor adherence among older participants. CONCLUSION: These data support components of the health beliefs model in predicting medication adherence among younger HIV-positive individuals. However, risk of adherence failure in those ages 50 years and older appears most related to neurocognitive status.

Variations in patterns of highly active antiretroviral therapy (HAART) adherence.

Strict adherence to highly active antiretroviral therapy (HAART) is necessary for successful suppression of HIV replication. A large number of individuals are not adherent, however, and the reasons for non-adherence are varied and complex. We utilized cluster analyses to identify subgroups of adherers in a sample of 222 HIV positive individuals whose HAART use was electronically monitored. Five distinct subgroups were identified, with characteristic variations across the week and over the course of the 4-week study. Additional comparisons of demographic and behavioral variables found the worst adherers to have higher rates of substance use, and that a group with higher rates of cognitive impairment had a consistent drop in adherence during the weekends. In addition, the group with the best adherence had more individuals over the age of 50 years. The results of the current study indicate that distinct subgroups of adherers may exist, and suggest that interventions designed to improve adherence can be designed to accommodate this variability in behavior.

Medication adherence in HIV-infected adults: effect of patient age, cognitive status, and substance abuse.

OBJECTIVE: To examine the predictors of antiretroviral adherence among HIV-infected adults, with a particular focus on advancing age, neuropsychological dysfunction, and substance abuse. DESIGN: : Prospective observational design. METHODS: Participants were 148 HIV-infected adults between the ages of 25 and 69 years, all on a self-administered antiretroviral regimen. Medication adherence was tracked over a one-month period using an electronic monitoring device (medication event monitoring system caps). All participants completed a comprehensive battery of neuropsychological tests as well as a structured psychiatric interview. RESULTS: The mean adherence rate for the entire cohort was 80.7%, with older patients (> or = 50 years) demonstrating significantly better medication adherence than younger patients (87.5 versus 78.3%). Logistic regression analyses found that older patients were three times more likely to be classified as good adherers (defined as > or = 95% adherent). Neurocognitive impairment conferred a 2.5 times greater risk of poor adherence. Among the older patients, those who were classified as poor adherers performed significantly worse on neuropsychological testing, particularly on measures of executive function and psychomotor speed. Current drug abuse/dependence, but not current alcohol abuse/dependence, was also associated with sub-optimal medication adherence. CONCLUSION: Although older age is associated with higher rates of antiretroviral adherence, older participants who were cognitively impaired showed disproportionate difficulty in adequately adhering to their medication regimen. As such, efforts to detect neuropsychological dysfunction, particularly among older patients, and a thorough assessment of substance abuse, appear to be essential for the effective treatment of HIV-infected adults.

Verbal and spatial working memory performance among HIV-infected adults.

Subtypes of working memory performance were examined in a cohort of 50 HIV-infected adults and 23 uninfected controls using an n-back paradigm (2-back) in which alphabetic stimuli were quasi-randomly presented to a quadrant of a computer monitor. In the verbal working memory condition, participants determined whether each successive letter matched the letter that appeared two previously in the series, regardless of spatial location. In the spatial working memory condition, participants determined whether each letter matched the spatial location of the letter that had appeared two previously, regardless of letter identity. The dependent variable was percent accuracy in each condition. Results of mixed model ANOVA revealed that the HIV-infected participants performed significantly worse than controls on both the verbal and spatial working memory tasks. A significant main effect for working memory condition was also present with both participant groups performing better on the spatial working memory task. These results, the first study of HIV-infected adults to directly compare verbal versus spatial working memory performance using the identical test stimuli across task conditions, suggests that HIV infection is associated with a decrement in working memory efficiency that is equally apparent for both verbal and spatial processing. These findings implicate central executive dysfunction as a likely substrate and provide the basis for hypothesizing that decline in working memory may contribute to other HIV-associated neuropsychological deficits.