An Examination of the Psychometric Properties of the Antiretroviral General Adherence Scale (AGAS) in Two Samples of HIV-Infected Individuals

This article reports on the development and psychometric properties of the Antiretroviral General Adherence Scale (AGAS) in two National Institutes of Health-funded projects: the Get Busy Living Project, a behavioral clinical trial to promote consistent use of antiretroviral therapy, and the KHARMA (Keeping Healthy and Active with Risk Reduction and Medication Adherence) Project, which addressed issues of adherence and risk reduction behavior in women. AGAS assesses the ease and ability of participants to take antiretroviral therapy according to a health care provider's recommendations. Data were analyzed from completed baseline assessments of the two studies. The AGAS was internally consistent in both samples. Content, construct, and criterion validity were established using factor analysis and correlations of total AGAS scores with two measures of adherence: electronic drug monitoring and an Adult AIDS Clinical Trials Group adherence scale. Viral load, CD4 cell counts, and depression scores were also examined. Reliability and validity of the AGAS were supported in both samples.

Key words: adherence, antiretroviral medications, reliability, psychometrics, validity