District Hospital Trauma Mental Health Screening Same-Day Discharge Destination and Post-Traumatic Stress Disorder Assessment Loss in Malawian Clinics: A Target-Trial Emulation of Transition Windows

Same-day discharge after trauma screening creates a transition window in which patients move from district hospital to home or to a clinic-based follow-up pathway, and the destination of that transition may determine whether post-traumatic stress disorder assessment occurs at all. the present analysis treats the transition window as a design parameter rather than a nuisance covariate and characterises the operating characteristics of a before-after-control-impact estimator for evaluating destination-conditional assessment loss in Malawian district hospital clinics. No observational data are used or claimed. Under a declared variance structure with between-cluster standard deviation of 6.0, residual standard deviation of 4.5 and intraclass correlation of 0.64, power was estimated across 2000 replications per design cell for cluster counts of 8, 16, 24 and 32 and effects of 3, 5 and 8 percentage points. Fifty-two clusters were required to detect a 5 percentage point difference at 80% power. The transition window is estimable as a causal contrast only when destination is treated as a time-varying assignment, and that the before-after-control-impact design recovers the destination-conditional contrast with acceptable operating characteristics at feasible cluster counts. The contribution is a design specification for transition-window emulation that separates destination from assessment loss and makes the identifying assumptions explicit.