Bryan J. Weiner ^1* Rosemary D. Meza ² Predrag Klasnja ³ Rebecca Lengnick-Hall ⁴ Gretchen J. Buchanan ⁵ Aaron Lyon ¹ Kayne D. Mettert ² Marcella H. Boynton ⁶ Byron J. Powell ⁴ Cara C. Lewis ²

• ¹ University of Washington, Seattle, United States
• ² Kaiser Permanente Washington Health Research Institute, Seattle, Washington, United States
• ³ University of Michigan, Ann Arbor, Michigan, United States
• ⁴ Washington University in St. Louis, St. Louis, Missouri, United States
• ⁵ Hennepin Healthcare Research Institute, Minneapolis, Minnesota, United States
• ⁶ University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States

Background: Opinion leadership, educational outreach visiting, and innovation championing are commonly used strategies to address barriers to implementing innovations and evidence-based practices in healthcare settings. Despite voluminous research, ambiguities persist in how these strategies work and under what conditions they work well, work poorly, or work at all. This paper develops middle-range theories to address this gap. Methods: Conceptual articles, systematic reviews, and empirical studies informed the development of causal pathway diagrams (CPDs). CPDs are visualization tools for depicting and theorizing about the causal process through which strategies operate, including the mechanisms they activate, the barriers they address, and the proximal and distal outcomes they produce. CPDs also clarify the contextual conditions (i.e., preconditions and moderators) that influence whether, and to what extent, the strategy's causal process unfolds successfully. Expert panels of implementation scientists and health professionals rated the plausibility of these preliminary CPDs and offered comments and suggestions on them. Theoretically, opinion leadership addresses potential adopters' uncertainty about likely consequences of innovation use (determinant) by promoting positive attitude formation about the innovation (mechanism), resulting in an adoption decision (proximal outcome), leading to innovation use (intermediate outcome). As this causal process repeats, penetration, or spread of innovation use, occurs (distal outcome). Educational outreach visiting addresses knowledge barriers, attitudinal barriers, and behavioral barriers (determinants) by promoting critical thinking and reflection about evidence and practice (mechanism), resulting in behavioral intention (proximal outcome), behavior change (intermediate outcome), and fidelity, or guideline adherence (distal outcome). Innovation championing addresses organizational inertia, indifference, and resistance (determinants) by promoting buy-in to the vision, fostering a positive implementation climate, and increasing collective efficacy (mechanisms), which leads to participation in implementation activities (proximal outcome), initial use of the innovation with increasing skill (intermediate outcome) and, ultimately, greater penetration and fidelity (distal outcomes). Experts found the preliminary CPDs plausible or highly plausible and suggested additional mechanisms, moderators, and preconditions, which were used to amend the initial CPD. The middle-range theories depicted in the CPDs furnish testable propositions for implementation research and offer guidance for selecting, designing, and evaluating these social influence implementation strategies in both research studies and practice settings.