ABSTRACT
Fidelity has long been a concern for research and practitioners aiming to improve outcomes for patients and populations, to enable valid causal inferences and accumulation of findings across studies, and to ensure equal access to best available evidence. Yet, the arguments in favour of high fidelity notwithstanding, adaptations are often unavoidable and might be necessary for achieving the necessary fit between the evidence-based intervention (EBI) and the context where it is used. The Value Equation (V = IN × C × IS) outlines value (V) as the result of an EBI (IN), in a context (C), given how well the implementation strategies (IS) resolve the tension between EBI and context. The tension can be resolved by adapting the context to the EBI and by adapting the EBI to context. Thus, the Value Equation proposes a way to reconcile fidelity and adaptation by positioning IS as tools for creating fit between an EBI and context, guided by an aspiration to maximize the value that can be achieved for patients, professionals, service organizations, and systems.
