TY - JOUR T1 - Evidence-based public health: not only whether it works, but how it can be made to work practicably at scale JF - Global Health: Science and Practice JO - GLOB HEALTH SCI PRACT SP - 253 LP - 258 DO - 10.9745/GHSP-D-14-00066 VL - 2 IS - 3 AU - James D Shelton Y1 - 2014/08/01 UR - http://www.ghspjournal.org/content/2/3/253.abstract N2 - Because public health must operate at scale in widely diverse, complex situations, randomized controlled trials (RCTs) have limited utility for public health. Other methodologies are needed. A key conceptual backbone is a detailed “theory of change” to apply appropriate evidence for each operational component. Synthesizing patterns of findings across multiple methodologies provides key insights. Programs operating successfully across a variety of settings can provide some of the best evidence. Challenges include judging the quality of such evidence and assisting programs to apply it. WHO and others should shift emphasis from RCTs to more relevant evidence when assessing public health issues. Evidence-based medicine (EBM) has greatly advanced the scientific validity, and presumably the effectiveness, of medical practice.1 The hallmark of EBM is the randomized controlled trial (RCT) with its potentially strong “internal validity” to answer precise questions under narrow conditions—generally whether and how well an intervention such as a drug works for individuals. Indeed, the Cochrane Review process—the mainstay of EBM—places RCTs on a pedestal above all other forms of evidence. There is a strong temptation to apply EBM methods and standards reflexively to public health. The World Health Organization (WHO), for example, relies heavily on the GRADE (grading of recommendations, assessment, development, and evaluation) system, which gives paramount importance to RCTs, to develop recommendations for public health issues.2 But public health must operate at large scale, addressing the needs of large populations across clinical, behavior, and structural platforms, and necessarily entails crucial operational issues, variability, and complexity as well as consideration of resource requirements and sustainability. Thus, because situations can vary so widely, “external validity” or generalizability of evidence to other situations is absolutely crucial for public health applications. Yet external validity is a severe weakness of the RCT methodology for public health decision-making. We need to know … ER -