A key issue in evaluating evidence is aligning the question(s) of interest with the appropriate outcome(s). Outcomes may be short-term, intermediate, or long-term. For example, some obesity prevention decisions will require evidence that relates directly to weight outcomes, while others may allow evidence related to intermediate behavioral outcomes.
Evaluations of interventions should also be sensitive to the nature of the intervention. For example, outcomes that are farther downstream from a policy change might also be of interest but would be less reflective of the specific effect of the change given the other influences that might have intervened in the interim. Quality considerations in assessing evidence, while based on the same principles, vary with the form or source of the evidence. Different types of evidence require different approaches to judging validity and other aspects of quality. Evaluating relevance to the context to which the question applies may be an additional critical step in any assessment of evidence for complex population-level interventions, requiring the application of criteria to judge the generalizability of the evidence.
Key Actions: (1) Develop a transparent and comprehensive summary of the evidence available on the decision that must be made, based on the information gathered by following the L.E.A.D. framework. (2) Include in this summary the question(s) asked by the decision maker; the strategy for gathering and selecting the evidence; an evidence table showing the sources, types, and quality of the evidence and the outcomes reported; and a concise summary of the evidence on why an action should be taken, what that action should be, and how it should be taken. (3) If obesity prevention actions must be taken when evidence is limited, examine the potential for blending the limited evidence with theory, professional experience, and local wisdom. (4) Use this summary to inform the decision-making process.
Once the potentially relevant evidence has been located and evaluated with the more broadly based, interdisciplinary view called for by the L.E.A.D. framework, the evidence needs to be synthesized and summarized to help inform the decision based on the question(s) asked. Taken together, the results of the overall evaluation of the evidence should assist in providing answers to why action should be taken, what action to take, and how to take it. Implicit in this process is the understanding that more than one type and source of evidence will be needed to inform decision making, and that there will be inevitable trade-offs between level of certainty and generalizability.
A standardized approach to assembling the results of evidence gathering and evaluation facilitates transdisciplinary discussion among stakeholders and presents evidence to decision makers in a usable form. A uniform language for drawing and describing conclusions signals the use of a uniform set of procedures to evaluate the evidence and improves clarity in communication. Clarity is particularly important when expertise from many different disciplines is required, each with its own jargon and methods.