Unravelling how and why the Antiretroviral Adherence Club Intervention works (or not) in a public health facility: A realist explanatory theory-building case study

Background: Although empirical evidence suggests that the adherence club model is more effective in retaining people living with HIV in antiretroviral treatment care and sustaining medication adherence compared to standard clinic care, it is poorly understood exactly how and why this works. In this paper, we examined and made explicit how, why and for whom the adherence club model works at a public health facility in South Africa. Methods: We applied an explanatory theory-building case study approach to examine the validity of an initial programme theory developed a priori. We collected data using a retrospective cohort quantitative design to describe the suppressive adherence and retention in care behaviours of patients on ART using Kaplan-Meier methods. In conjunction, we employed an explanatory qualitative study design using non-participant observations and realist interviews to gain insights into the important mechanisms activated by the adherence club intervention and the relevant contextual conditions that trigger the different mechanisms to cause the observed behaviours. We applied the retroduction logic to configure the intervention-context-actor-mechanism-outcome map to formulate generative theories. Results: A modified programme theory involving targeted care for clinically stable adult patients (18 years+) receiving antiretroviral therapy was obtained. Targeted care involved receiving quick, uninterrupted supply of antiretroviral medication (with reduced clinic visit frequencies), health talks and counselling, immediate access to a clinician when required and guided by club rules and regulations within the context of adequate resources, and convenient (size and position) space and proper preparation by the club team. When grouped for targeted care, patients feel nudged, their self-efficacy is improved and they become motivated to adhere to their medication and remain in continuous care. Conclusion: This finding has implications for understanding how, why and under what health system conditions the adherence club intervention works to improve its rollout in other contexts.