LAUSR

This study examined how teachers discuss various factors as impacting their ability to execute with fidelity the Michigan Model for Health (MMH), an evidence-based health universal prevention curriculum widely adopted throughout Michigan. Researchers have found a robust relationship between fidelity and participant outcomes, including in schools. While previous studies have identified barriers that inhibit fidelity, few have focused on identifying key barriers and deepening our understanding of how these factors influence intervention fidelity. We conducted a thematic analysis using the reflexive thematic approach to identify key barriers and facilitators and deepen our understanding of how these factors influence MMH implementation. Guided by the Consolidated Framework for Implementation Research (CFIR) and the Implementation Outcomes Framework, we conducted semistructured interviews with 23 high school health teachers across Michigan. Teachers identified intervention characteristics (e.g., design quality, packaging, and program adaptability), student needs (e.g., trauma exposure, substances), and the fit between the intervention and the context as factors that contributed to acceptability. They also discussed the curriculum and its alignment with their teaching style and/or experiences as contributing to fidelity. Teachers shared how they would often go "off protocol" to improve intervention-context fit and meet students' needs. Our results identified acceptability, a perceptual implementation outcome, as demonstrating an important role in shaping the relationship between CFIR factors and fidelity. Results provide guidance for systematically designing implementation strategies that address key barriers to improve acceptability, enhance fidelity, and ultimately achieve desired public health objectives.