Performance of a short, self-report adherence scale in a probability sample of persons using HIV antiretroviral therapy in the United States.

backgroundExcellent adherence to HIV antiretroviral therapy (ART) remains a cornerstone of HIV care. A three-item adherence self-report scale was recently developed and validated, but the scale has not been previously tested in a nationally representative sample.

designWe administered the adherence scale to participants in the Centers for Disease Control and Prevention's Medical Monitoring Project, which is a probability sample of US adults with diagnosed HIV.

methodsWe combined sociodemographic and clinical participant data from three consecutive cycles of the Medical Monitoring Project (6/2015-5/2018). We used medical record reviews to determine most recent viral load, and whether viral loads were suppressed at all measurement points in the past 12 months. We describe the relationship between adherence scale score and two measures of viral load suppression (most recent and sustained), and estimate linear regression models using sampling weights to determine independent predictors of ART adherence scores.

resultsOf those using ART, the median adherence score was 93 (100 = perfect adherence), and the standardized Cronbach's alpha was 0.83. For both measures of viral load suppression, the relationship with the adherence score was generally linear; there was no 'cutoff' point indicating good vs. poor adherence. In the multivariable model, younger age, nonwhite race, poverty, homelessness, depression, binge-drinking, and both non-IDU and IDU were independently associated with lower adherence.

conclusionThe adherence measure had good psychometric qualities and a linear relationship with viral load, supporting its use in both clinical care and research. Adherence interventions should focus on persons with the highest risk of poor adherence.