District Hospital Trauma Survivor Mental Health Screening Consent Withdrawal Timing and Post-Traumatic Stress Disorder Documentation Integrity in Tanzanian Referral Facilities: A Target-Trial Emulation of Consent Revocation Windows

Consent withdrawal in trauma survivor mental health screening creates a documentation problem that existing research has not addressed: when a survivor revokes consent after a screening instrument has been administered but before post-traumatic stress disorder (PTSD) status is recorded, the resulting record is neither a valid positive nor a valid negative, and the integrity of the clinical dataset depends on when withdrawal occurs relative to documentation. Because no primary data were collected, the analysis characterises the operating characteristics of a before-after-control-impact (BACI) estimator under a declared variance structure with an intraclass correlation of 0.64, between-cluster standard deviation of 6.0 and residual standard deviation of 4.5. 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 design required 52 clusters to detect a 5-percentage-point effect at 80% power. Consent revocation timing should be treated as a design variable rather than a nuisance, and that documentation integrity in PTSD screening is a function of the alignment between revocation windows and the target-trial protocol.