Geographic variation in loss to follow-up from HIV care in Tanzania and its association with pharmacy refill adherence in routine programme data

Abstract Background Sustained retention in HIV care is essential for achieving durable viral suppression and controlling the HIV epidemic. Loss to follow-up (LTFU) remains a persistent challenge in sub-Saharan Africa and shows substantial geographic variation. However, nationally representative analyses of routine monitoring data remain limited. Pharmacy refill data provide a scalable and objective approach for identifying individuals at risk of disengaging from care. We assessed the magnitude, spatial distribution, and predictors of LTFU among people living with HIV (PLHIV) receiving antiretroviral therapy (ART) across 26 mainland regions of Tanzania. Methods We conducted a retrospective cohort analysis using routinely collected program data from the National Care and Treatment Clinic (CTC-2) database of PLHIV receiving ART in Tanzania between 2017 and 2021. LTFU was defined as no recorded clinic visit for ≥180 days after the last scheduled appointment, consistent with monitoring definitions used by the National AIDS and Sexually Transmitted Infections Control Programme (NASHCoP). Pharmacy refill adherence was calculated longitudinally and categorized as good (≥85%) or poor (