Abstract
BACKGROUND: Theories, models, and frameworks (TMFs) are central to the development and evaluation of implementation strategies supporting evidence-based practice (EBP). However, evidence on how and to what extent TMFs are used in implementation trials remains limited. PURPOSE: This study aimed to examine the nature and extent of TMF use in implementation trials, identify which TMFs are most frequently employed, and explore temporal trends in their use. METHODS: A secondary analysis was conducted on 151 randomized trials of implementation strategies targeting EBP in nursing. Trials and their protocols were coded in NVivo 14 using a framework adapted from Painter's continuum of theory use (2005) and Michie and Prestwich's theory coding scheme (2010). The framework categorized theory use as "informed by," "applied," "tested," or "built" theory. Descriptive statistics were calculated in R, and temporal trends in TMF use across categories were analyzed. RESULTS: Among the 151 trials, 54 (36%) reported using a TMF. Of these, most applied TMFs to guide implementation strategy design (28%), followed by justifying the study's purpose, aims, or objectives (15%). Testing theory was infrequent (9%), and no trials reported refining or building theory. Classic theories, such as the theory of planned behavior and social cognitive theory, were the most frequently cited. No clear temporal trend was found in TMF use across the categories. CONCLUSIONS: TMFs remain underutilized in implementation trials, with their application primarily limited to justifying study rationale or informing implementation strategy development. Greater emphasis on the testing and refinement of TMFs is recommended to advance implementation science. REGISTRATION INFORMATION: Review registration: PROSPERO CRD42019130446.