Dental hygiene therapy caregiver-supervised brushing intervals and early childhood caries incidence in Mozambican community health-worker networks: a target-trial emulation of supervision frequency

Supervision frequency is the modifiable lever in caregiver-supervised brushing programmes, yet the interval between professional or community health-worker contacts is rarely treated as a design parameter with estimable operating characteristics. No observational data are used or claimed. The analysis characterises the design under a declared variance structure with between-cluster standard deviation 6.0, residual standard deviation 4.5 and intraclass correlation 0.64, across cluster counts of 8, 16, 24 and 32 and effect sizes of 3, 5 and 8 percentage points, with 2000 replications per design cell. Power was estimated for the interaction term, and the minimum detectable effect at 80% power was derived for each cluster count. The design requires 54 clusters to detect a 5 percentage point effect at 80% power under the declared variance structure. The before-after-control-impact estimator is defensible for supervision-interval emulation only when cluster counts are set against the intraclass correlation rather than against the nominal sample of children, and it specifies the conditions under which the design yields interpretable estimates of supervision frequency.