Community Mental Health Service Tobacco Cessation Counselling Integration into HIV Clinics and Sustained Virological Suppression in Ugandan Districts: A Difference-in-Differences Estimation of Integrated Care Exposure

Tobacco use among people living with HIV accelerates immunosuppression and undermines virological suppression, yet cessation counselling remains poorly integrated into HIV care in Uganda. The design exploits staggered rollout of integrated counselling packages across districts, comparing pre- and post-integration changes in suppression among clinic-attending people living with HIV in exposed versus unexposed districts. The proposed estimator is a two-way fixed-effects difference-in-differences model with district and year fixed effects, clustered standard errors, and event-study diagnostics to assess parallel pre-trends. The paper specifies the exposure definition, outcome measurement, confounding control strategy, and sensitivity analyses required to support causal interpretation. It also addresses implementation heterogeneity, contamination across districts, and the distinction between counselling receipt and counselling fidelity. The contribution is a pre-specified, transparent estimation framework that can be executed once district-level integration and virological outcome data become available, and that clarifies the assumptions under which integrated mental health and tobacco cessation services can be expected to improve HIV treatment outcomes in Ugandan district health systems.