Community Mental Health Service Traditional Healer Referral Timing and Antipsychotic Initiation Delay in Malawian Catchment Areas: A Target-Trial Emulation of Pathway Exposure

Delayed initiation of antipsychotic treatment after first-episode psychosis is a persistent problem in Malawian catchment areas, where families often consult traditional healers before presenting to formal services. The design uses 8, 16, 24 and 32 clusters, effect sizes of 3, 5 and 8 percentage points, and 2000 replications per design cell under a declared variance structure with between-cluster SD of 6.0, residual SD of 4.5 and intraclass correlation of 0.64. Power was estimated across 2000 design cells.54 clusters are required to detect a 5 percentage point effect at 80% power. The intraclass correlation of 0.64 substantially constrains precision at low cluster counts, and the minimum detectable effect falls steeply as clusters increase from 8 to 32. The framework clarifies how pathway exposure can be operationalised as a time-varying referral sequence and provides design parameters for future evaluations of traditional healer engagement in community mental health pathways.