Community Mental Health Service Teleconsultation Bandwidth Allocation and Diagnostic Concordance in Rwandan District Hospitals: A Stepped-Wedge Estimation of Rural Connectivity Exposure

Teleconsultation in community mental health services depends on bandwidth that district hospitals in rural Rwanda rarely control, and the stepped-wedge designs used to evaluate such programmes are usually powered as if connectivity exposure were a fixed attribute of clusters rather than a time-varying, partially observed condition. the present analysis treats the stepped-wedge trial of bandwidth allocation as a design problem and characterises the operating characteristics of a before-after-control-impact estimator under a declared variance structure. No observational data are used or claimed. The analysis fixed the between-cluster standard deviation at 6.0, the residual standard deviation at 4.5 and the intraclass correlation at 0.64, and evaluated power 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. Under these parameters, 52 clusters are required to detect a 5 percentage point improvement in diagnostic concordance at 80% power, a requirement that exceeds every cluster count examined and that most district-level evaluations in the region cannot meet. Stepped-wedge teleconsultation studies should be planned around the minimum detectable effect at the cluster counts actually available, and that concordance endpoints with high intracluster correlation demand either more clusters or a different estimand. The contribution is a design-characterisation framework that makes the power consequences of rural connectivity exposure explicit before data collection begins.