Adherence and Attrition in Public Fluoride Varnish Programs: A Mixed-Methods Systematic Review.

BACKGROUND: Public fluoride varnish (FV) programs, often delivered as part of a multi-component oral preventive package, rely on the patient's continued participation. However, continued adherence is often poor in real-world settings. AIM: To synthesize child, family, provider, and systemic level barriers and facilitators influencing adherence and attrition in public FV programs for children < 18 years in multi-ethnic high-income countries. DESIGN: Systematic review was conducted in accordance with PRISMA 2020. Six databases were searched for studies reporting barriers and facilitators to repeated FV applications. RESULTS: From 3616 records, 22 studies were included. Child-level barriers included behavioral distress, sensory aversion, and temporary medical exclusions. Family-level barriers included caregiver capacity, health literacy, and mobility. Provider-level barriers included workforce constraints, training, role boundaries limiting task-sharing, and weak school/community coordination. System-level barriers included inequitable reach to high-risk groups and geographic constraints. Facilitators included culturally safe, relationship-based engagement, task-sharing, school/community-based delivery with active follow-up systems, and child-centered engagement strategies. Meta-analysis demonstrated a pooled attrition rate of 23% (95% CI 8%-43%, n = 14 455). CONCLUSION: Adherence and attrition in public FV programs are shaped by interacting determinants across child, family, provider, and system levels. Retention should be considered when designing and implementing these programs. TRIAL REGISTRATION: CRD420251044425 (PROSPERO).