Charting progress in learning health systems: A systematic review of 5 years of definitions, models, and frameworks.

Introduction: Since being introduced by the Institute of Medicine (IoM) in 2007, the learning health system (LHS) concept has gained traction as a promising solution for achieving systems-level healthcare transformation. This review of the LHS literature consolidates current understanding of LHS definitions, models, frameworks, and underlying theory, relative to their initial conceptualization by the IoM. Methods: Three academic databases (PubMed, Embase, and Scopus) were searched for peer-reviewed literature between 2018 and 2023. Articles were included that explicitly focused on LHSs and described an LHS definition, model, or framework. Extracted article information included key article characteristics and article type; LHS definition(s) and their reference(s); components of LHS models or frameworks; and any reported theories underpinning LHS models or frameworks. Extracted data were examined using thematic and visual network analyses, and practical examples of how the domains of an LHS can be actualized in health settings were synthesized. Results: The majority of the 226 included articles were nonempirical (47%) and originated from high-income countries (97%), with a significant portion from the United States (62%). A third of articles described an LHS implemented in a real-world setting (35%). A significant majority (82%) provided a definition of an LHS, with key concepts centering around "knowledge to practice," "workplace culture," and "informatics." Over half of included articles described an LHS model or framework. From thematic deductive-inductive coding of 145 LHS models and frameworks, most identified aspects related to Science and Informatics (83%) and a Continuous Learning Culture (81%), with the most prevalent sub-domain being Supportive System Competencies (76%). Implementation science was the most used theory to underpin existing models and frameworks. Conclusions: By dissecting LHS definitions, models, and frameworks, we present an integrated framework that can serve as a useful tool for LHS researchers, clinicians, and policymakers working to improve health system performance and outcomes.