Understanding patients' adherence to antiretroviral therapy: a mixed-methods study in Arusha, Tanzania

Background: Over one million HIV-positive people in Africa are taking antiretroviral therapy (ART), and this number is increasing. Essential to the expansion of ART is ensuring patients' optimal adherence to therapy. This study combined qualitative and quantitative methods to understand ART adherence at one site in Tanzania where patients received free medication. The study measured ART adherence, identified factors associated with poor adherence, and explored how the social environment of patients' lives supported adherence. A theoretical framework using the Social Cognitive Theory (SCT) and social support guided the study. Methods: Semi-structured interviews were conducted in Kiswahili with 36 adult ART patients and 6 health care providers. Patients described their experiences taking ART and managing adherence and providers described their experiences caring for patients. A structured survey was conducted with 340 patients. Adherence was measured by self report, and patients were identified as having poor adherence if they took less than 95% of their pills during either the previous four days or one month. The survey measured correlates of adherence informed by the SCT, along with demographic and treatment variables. Factors associated with adherence were considered in a logistic regression model. Results: Only 5.9% (20/340) of patients reported poor adherence. Poor adherence was associated with: being young (19-30 years, vs. 31-40 years; OR=4.26, 95% CI 1.33-13.60); being old (over 50 years, vs. 31-40 years; OR=7.59, 95% CI 2.10-27.43); having lower perceived quality of patient-provider interaction (for each one-point decrease, OR=3.18, 95%CI 1.29-7.83); and ever missing a clinic appointment (OR=3.75, 95% CI 1.29-10.89). Semi-structured interviews identified five factors to explain optimal adherence. First, respondents experienced improved health on ART, which motivated adherence. Second, they linked pill-taking with routine activities. Third, they were motivated to stay healthy to meet family responsibilities. Fourth, material and emotional support from others facilitated adherence. Finally, respondents trusted health care providers' instructions to adhere. Conclusions: Adherence was high in this sample. Interventions to improve and sustain adherence should focus within the clinic to improve interactions between patients and providers and outside the clinic to bolster patients' social support. Different strategies may be necessary according to patients' ages