Dental hygiene therapy oral cancer screening yield and tobacco-cessation referral uptake in Zimbabwean primary care: a regression-discontinuity analysis of age-eligibility thresholds

Zimbabwe's primary-care oral health guidelines tie eligibility for free oral cancer screening to an age threshold, but the yield of that screening and the uptake of tobacco-cessation referral that follows it have not been estimated against a credible counterfactual. The design is specified for a primary-care population in which dental hygiene therapists deliver screening and referral, and it treats the threshold as a source of quasi-random variation in exposure. It also specifies how the design distinguishes screening yield from case ascertainment and how it separates referral uptake from referral offer. The contribution is methodological: it converts an administrative eligibility rule into an identification strategy for dental hygiene therapy research in a low-resource African primary-care setting, and it specifies the quantities that a field implementation would need to report. The design is presented as a protocol for prospective evaluation, not as a report of completed fieldwork.