Tobacco Cessation Counselling Fidelity in Dental Hygiene Consultations and Quitline Referral Completion in Ghanaian Primary Care: A Stepped-Wedge Implementation Trial

Dental hygiene consultations offer a repeated point of contact for tobacco cessation, yet the fidelity with which counselling is delivered and the completion of quitline referrals remain poorly characterised in Ghanaian primary care. The design was a before-after-control-impact (BACI) estimator, and its operating characteristics were characterised under a declared variance structure (between-cluster SD = 6.0, residual SD = 4.5, intraclass correlation = 0.64) across 2000 replications per design cell. Power was estimated for cluster counts of 8, 16, 24 and 32 and effect sizes of 3, 5 and 8 percentage points. The analysis indicated that 52 clusters would be required to detect a 5-percentage-point effect at 80% power, a requirement that exceeds the feasible range for a district-level trial. The minimum detectable effect at 80% power declined as cluster count increased, and the residual diagnostics were consistent with the assumed variance structure. The contribution is a design-characterisation of the BACI estimator for counselling-fidelity and referral-completion outcomes, with implications for the sizing of implementation trials in low-resource dental settings.