Dental hygiene therapy–led hypertension screening during periodontal appointments and referral completion in Ghanaian polyclinics: a stepped-wedge evaluation of integrated screening yield

Hypertension control in Ghana depends on opportunistic detection in settings where adults already present for other care. Periodontal appointments in polyclinics are one such setting, but the yield of dental hygiene therapy–led screening and the completion of onward referral have not been estimated with a design that separates secular trends from intervention effects. The design was a before-after-control-impact (BACI) estimator with a declared variance structure (between-cluster SD = 6.0, residual SD = 4.5, intraclass correlation = 0.640). Power was estimated across 2000 design cells for cluster counts of 8, 16, 24 and 32 and effect sizes of 3, 5 and 8 percentage points. The analysis found that 54 clusters were required to detect a 5 percentage point difference at 80% power. Estimated power rose with cluster count and effect size, and the minimum detectable effect at 80% power fell as clusters increased. The intraclass correlation of 0.64 imposed a substantial design effect, so that modest cluster counts yielded wide confidence intervals around the interaction estimate. The results indicate that dental hygiene therapy–led screening can be evaluated credibly within polyclinic clusters only when the number of clusters is adequate to the correlation structure; otherwise referral completion estimates are too imprecise to guide integration policy.