BACKGROUND: Social and structural determinants of health (SDoH) are associated with tuberculosis (TB) outcomes but often unaddressed in TB care programs. We sought to describe the mechanism by which SDoH impact completion of TB diagnostic evaluation in Uganda using an implementation science framework rooted in behavioral theory. METHODS: Trained research staff interviewed 24 purposively sampled adults undergoing TB diagnostic evaluation at six community health centers in Uganda between February-August 2019. Framework analysis was used to construct themes linked to SDoH across the TB diagnostic evaluation cascade of care. Themes were then mapped to domains of the capability, opportunity, and motivation behavior change model (COM-B). RESULTS: Barriers related to SDoH were identified across the diagnostic evaluation cascade of care and associated with domains central to uptake of testing and treatment. These included: limited knowledge about TB diagnosis and treatment (psychological capability)
low socioeconomic status and competing financial priorities (physical opportunity)
internalized and anticipated stigma of TB diagnosis, lack of social support programs and limited social support/social capital (social opportunity, reflective motivation)
trust (or distrust) in the government health facility to provide quality care (reflective motivation)
and fear and shame about worsening poverty (automatic motivation). Facilitators to engagement with the TB cascade of care included encouragement from friends and family to seek testing (automatic motivation, social opportunity), and trust that healthcare providers were acting in their best interests (social opportunity). CONCLUSIONS: Biomedical interventions alone are unlikely to address the spectrum of SDoH-related barriers to equitable completion of TB diagnostic evaluation. Linking barriers to a behavior change model such as COM-B may help guide the design and evaluation of appropriate people-centered strategies that integrate social and economic supports with clinical and public health programs or services.