The World Health Organization estimates that 13.2 million deaths in 2005 resulted from causes for which proven, low-cost prevention and treatment interventions exist.1,2 Ten years later, while fewer preventable deaths occurred, still more than 10 million deaths in 2015 were attributed to causes with known, low-cost prevention or treatment options.1 Since 2005, there have been significant reductions in the excess mortality that low- and middle-income countries (LMICs) experience relative to high-income countries (HICs), particularly due to declining child mortality and deaths due to HIV/AIDS and malaria.1,2 Yet, despite these reductions in mortality, millions of lives are lost each year from preventable or treatable illnesses and health problems.1,2
All women need access to antenatal care in pregnancy, skilled care during childbirth, and care and support in the weeks after childbirth.3 Nonetheless, millions of women do not receive these lifesaving services. In 2015 alone, an estimated 300,000 women died from preventable causes related to only to pregnancy and childbirth,4 even though the solutions to prevent or manage life-threatening complications in pregnancy and childbirth are well known.
A similar gap exists in malaria prevention. An estimated 439,000 malaria deaths occurred worldwide in 2015,1 even though insecticide-treated mosquito nets and indoor spraying of insecticides are known to be effective strategies for preventing and reducing malaria transmission.5 Although the consequences of contracting malaria are severe, nearly half of the population at risk does not sleep under a treated net, and the proportion of the population at risk benefiting from indoor residual spraying declined from a peak of 5.7% globally in 2010 to 3.1% in 2015.5
As these examples attest, the issue is not whether effective health interventions exist, but rather whether effective health interventions are implemented to reach those who would benefit from them. While the knowledge exists to solve many of the world’s health problems, a persistent gap remains between knowing what to do (the “know”) and putting that knowledge into action (the “do”). It is this gap that the field of implementation science aims to address.
IMPLEMENTATION SCIENCE DEFINED
Implementation science seeks to close the “know-do gap” by systematically identifying and addressing the barriers that hinder access to and use of effective health interventions. Put differently, implementation science involves the systematic study of both the processes used to implement effective health interventions, as well as the contextual factors that affect these processes.6 As is common in rapidly developing scientific fields, consensus has yet to emerge on the scope of implementation science or its relationship to other emerging fields.7
Definitions of implementation science vary from relatively narrow formulations, such as “the study of methods to promote the uptake of research findings into routine healthcare in clinical, organizational or policy contexts,”8 to broad formulations such as “scientific inquiry into [all] questions concerning implementation.”9...