Abstract
BACKGROUND: Antiretroviral therapy (ART) is the cornerstone of HIV clinical care and is increasingly recognized as a key component of HIV prevention. However, the benefits of ART can be realized only if HIV-infected persons maintain high levels of adherence. METHODS: We present interview data (collected from June 2007 through September 2008) from a national HIV surveillance system in the United States-the Medical Monitoring Project (MMP)-to describe persons taking ART. We used multivariate logistic regression to assess behavioral, sociodemographic, and medication regimen factors associated with three measures that capture different dimensions of nonadherence to ART: dose, schedule, and instruction. RESULTS: The use of ART among HIV-infected adults in care was high (85%), but adherence to ART was suboptimal and varied across the three measures of nonadherence. Of MMP participants currently taking ART, the following reported nonadherence during the past 48 hours: 13% to dose, 27% to schedule, and 30% to instruction. The determinants of the three measures also varied, although younger age and binge drinking were associated with all aspects of nonadherence. CONCLUSION: Our results support the measurement of multiple dimensions of medication-taking behavior in order to avoid overestimating adherence to ART.