District Hospital Trauma Mental Health Screening Queue Prioritization Rules and Post-Traumatic Stress Disorder Detection Yield in Rwandan Clinics: A Stepped-Wedge Analysis of Triage Order Effects

Queue prioritization rules in district hospital trauma screening determine which survivors are assessed for post-traumatic stress disorder (PTSD) first, yet the statistical consequences of triage order for detection yield remain uncharacterized. 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 found that 52 clusters were required to detect a 5-percentage-point effect at 80% power, and that minimum detectable effect declined monotonically with cluster count. Kernel density estimates of power across replications showed substantial overlap between adjacent design cells at low cluster counts, indicating that triage-order effects of clinical interest are not reliably distinguishable from sampling variation in small stepped-wedge designs. The results imply that district hospitals implementing queue prioritization rules should anticipate cluster counts well above those typical of single-facility audits, and that detection-yield claims from small triage-order studies should be treated as hypothesis-generating rather than confirmatory.