Policy Points More rigorous methodologies and systematic approaches should be encouraged in the science of scaling. This will help researchers better determine the effectiveness of scaling, guide stakeholders in the scaling process, and ultimately increase the impacts of health innovations. The practice and the science of scaling need to expand worldwide to address complex health conditions such as noncommunicable and chronic diseases. Although most of the scaling experiences described in the literature are occurring in the Global South, most of the authors publishing on it are based in the Global North. As the science of scaling spreads across the world with the aim of reducing health inequities, it is also essential to address the power imbalance in how we do scaling research globally.
Context: Scaling of effective innovations in health and social care is essential to increase their impact. We aimed to synthesize the evidence base on scaling and identify current knowledge gaps.
Methods: We conducted an umbrella review according to the Joanna Briggs Institute Reviewers' Manual. We included any type of review that 1) focused on scaling, 2) covered health or social care, and 3) presented a methods section. We searched MEDLINE (Ovid), Embase, PsycINFO (Ovid), CINAHL (EBSCO), Web of Science, The Cochrane Library, Sociological Abstracts (ProQuest), Academic Search Premier (EBSCO), and ProQuest Dissertations & Theses Global from their inception to August 6, 2020. We searched the gray literature using, e.g., Google and WHO-ExpandNet. We assessed methodological quality with AMSTAR2. Paired reviewers independently selected and extracted eligible reviews and assessed study quality. A narrative synthesis was performed.
Findings: Of 24,269 records, 137 unique reviews were included. The quality of the 58 systematic reviews was critically low (n = 42). The most frequent review type was systematic review (n = 58). Most reported on scaling in low- and middle-income countries (n = 59), whereas most first authors were from high-income countries (n = 114). Most reviews concerned infectious diseases (n = 36) or maternal-child health (n = 28). They mainly focused on interventions (n = 37), barriers and facilitators (n = 29), frameworks (n = 24), scalability (n = 24), and costs (n = 14). The WHO/ExpandNet scaling definition was the definition most frequently used (n = 26). Domains most reported as influencing scaling success were building scaling infrastructure (e.g., creating new service sites) and human resources (e.g., training community health care providers).
Conclusions: The evidence base on scaling is evolving rapidly as reflected by publication trends, the range of focus areas, and diversity of scaling definitions. Our study highlights knowledge gaps around methodology and research infrastructures to facilitate equitable North-South research relationships. Common efforts are needed to ensure scaling expands the impacts of health and social innovations to broader populations.
Keywords: capacity building; delivery of health care; diffusion of innovation; evidence-based practice; health plan implementation; review literature as topic; scalability; scaling science.
© 2023 The Authors. The Milbank Quarterly published by Wiley Periodicals LLC on behalf of The Milbank Memorial Fund.