District Hospital Trauma Mental Health Screening Attrition After Physical Injury Recovery Milestone Discharge and Post-Traumatic Stress Disorder Detection in South African Clinics: A Target-Trial Emulation of Care Transition Windows

Physical recovery from traumatic injury is routinely treated as a discharge milestone, yet the weeks that follow discharge from district hospital trauma wards are precisely when post-traumatic stress disorder (PTSD) is most likely to become detectable and least likely to be detected. The framework is evaluated through a replication-based design analysis of the before-after-control-impact estimator under a declared variance structure (between-cluster SD = 6.0, residual SD = 4.5, intraclass correlation = 0.64). Power was estimated across 2000 replications per design cell for cluster counts of 8, 16, 24 and 32 and effect sizes of 3, 5 and 8 percentage points. The analysis identifies the cluster count at which 80% power is reached for a 5 percentage point effect and characterises the minimum detectable effect at each cluster count. The contribution is a design specification that treats the care transition window, rather than the trauma ward, as the unit of inference, and that makes explicit the attrition process that any evaluation of post-discharge PTSD screening must confront.