Measures and Models of Reach in Healthcare Interventions in LMICs:  A Systematic Review

<ns3:p>Background The dual burden of communicable and non-communicable diseases, coupled with growing multiple chronic conditions (MLTCs), poses a pressing challenge for health systems in low- and middle-income countries (LMICs), such as South Africa. In response, multiple healthcare interventions have been developed to strengthen care. Understanding and measuring reach and the extent to which healthcare interventions engage their intended populations is crucial. This review aims to critically examine how reach is defined, conceptualized, and measured in healthcare and complex health systems interventions in LMICs. It also evaluates the methods, models, and frameworks used; highlighting their strengths and limitations; and assesses how equity and representativeness are addressed. Methods Drawing on Whittemore and Knafl’s integrative review methodology, the review systematically synthesizes empirical and theoretical literature. Searches were conducted across multiple databases, guided by explicit inclusion and exclusion criteria. Rigorous data extraction, utilizing both technical and conceptual matrices, categorized reach definitions, measurement approaches, and conceptual orientations. Results Reach was conceptualized across three communities of practice: coverage-focused (emphasizing quantitative metrics like participation rates, n=15), relational (exploring contextual dimensions such as trust and accessibility, n=6), and systemic (addressing structural dimensions like health system readiness, n=5). Some studies employed (n=4) hybrid approaches. Coverage studies emphasized quantitative metrics, while relational and systemic approaches explored contextual and structural dimensions such as trust, accessibility, and health system readiness. While RE-AIM was frequently referenced, other diverse frameworks (e.g., Consolidated Framework for Implementation Research; Primary Health Care Performance Initiative) were also utilized. Crucially equity and representativeness were often acknowledged but rarely operationalized in measurement. Conclusion This review highlights the multidimensional nature of reach and underscores the urgent need for improved conceptual clarity and methodological rigor in its measurement. To enhance equitable implementation, future efforts in LMICs must integrate both quantitative and contextual approaches, better aligning measurement practices with lived experiences.</ns3:p>