A Simple Visual Analog Scale is a Valuable Tool to Assess Self-ReportedAdherence in HIV-Infected Patients on Antiretroviral Treatment in aResource-Limited Setting

Background: Adherence assessment in HIV-infected individuals under antiretroviral therapy (ART) is essential. The assessment tool should be reliable and easy to apply in routine clinical practice. The goal of this study was to evaluate a pictogram-enhanced visual analog scale (VAS) suitable for illiterate patients to assess self-reported adherence in ART-treated HIV-infected individuals in a resource-limited setting. Methods: Adherence of 299 HIV-infected individuals on ART for ≥ 6 months attending an HIV-clinic in rural Tanzania was prospectively assessed 1-3 months (visit V1) and 6-9 months (V2) after a healthcare provider training in patient-centered communication by various measures: 1) 1-10 pictogram-combined Likert VAS, 2) standardized questionnaire, 3) therapeutic drug monitoring (TDM) of ART-compounds and 4) plasma HIV-RNA. Results: 94% of the study population had no formal or only primary education. Individuals with non-adherence were detected in 17.2% by VAS (score ≤ 9) and in 10.7% by questionnaire (≥ 1 missed ART-dose/4weeks) at V1. The detection rate declined to a lesser extent with VAS (11.7%, p=0.06) compared to the questionnaire (5.7%, p=0.016) at V2. VAS strongly correlated with the questionnaire (kappa>0.50, p<0.0001). Test agreements between TDM and VAS (kappa ≤ 0.200) and between HIV-RNA and VAS (kappa ≤ 0.220) were weak to fair, but slighly superior compared to the questionnaire (kappa ≤ 0.180 and ≤ 0.060, respectively). Conclusion: The VAS is a valuable tool for assessing self-reported adherence in illiterate HIV-infected individuals. It is inexpensive, rapid, and easier to apply than the questionnaire. Its use should be considered in resource-limited countries where more complex measures may not be feasible.