Reliability and Validity of a Brief Self-Report Adherence Measure among People with HIV Experiencing Homelessness and Mental Health or Substance Use Disorders.

The study examines the reliability and validity of a 3-item self-report adherence measure among people with HIV (PWH) experiencing homelessness, substance use, and mental health disorders. 336 participants were included from nine sites across the US between September 2013 and February 2017. We assessed the validity of a self-report scale for adherence to antiretroviral therapy by comparing it with viral load (VL) abstracted from medical records at baseline, 6, 12, and 18 months. The items had high internal consistency (Cronbach's alpha coefficients at each time point were > 0.8). The adherence scale scores were higher in the group that achieved VL suppression compared to the group that did not. The c-statistic for the receiver-operating characteristic curves pooled across time points was 0.77 for each adherence sub-item and 0.78 for the overall score. The self-report adherence measure shows good internal consistency and validity that correlated with VL suppression in homeless populations.