Advancing Systematic Review Methodology to Better Inform Food and Nutrition Policy

Abstract

Systematic reviews critically assess research studies relevant to a particular research question. The USDA's Nutrition Evidence Library (NEL) utilizes state‐of‐the‐art methodology to conduct systematic reviews evaluating scientific evidence related to food and nutrition to answer questions that inform federal policies and programs, such as the Dietary Guidelines for Americans. The NEL has continually advanced its process to stay at the forefront of the systematic review field. However, the key steps of the NEL process remain the same, including: 1) developing systematic review questions; 2) searching, screening, and sorting the literature; 3) extracting data and assessing the risk of bias of the research; 4) describing and synthesizing the evidence; 5) developing conclusion statements and grading the evidence; and 6) identifying research recommendations. Advancements to the NEL process include: 1) integrating broader input to develop, refine, and prioritize systematic review questions; 2) incorporating key definitions and confounders into the analytic framework, a visual representation of the systematic review project; 3) developing a standard inclusion/exclusion template to promote consistency across reviews and expanding the inclusion/exclusion criteria list; 4) conducting a duplication assessment to determine if other high‐quality systematic reviews exist which answer the prioritized questions; 5) combining title and abstract screening; 6) integrating dual‐screening of the literature; 7) revising the quality assessment tool to be tailored by study design and to focus on internal validity assessment, opposed to study quality; 8) revising the NEL grading rubric used to grade the totality of the evidence; 9) integrating a step to define research recommendations as a component of the evidence review, opposed to after the process; and 10) creating technical abstracts and plain‐language summaries that summarize the completed systematic reviews. In addition to process improvements, the NEL has enriched the training of experts with whom it works to streamline the conducting of systematic reviews. Also, the NEL has expanded its website by including additional systematic review materials, which increases the transparency of the process and makes nutrition research publicly available. NEL systematic reviews will be used to illustrate these improvements and to facilitate discussions which can contribute to advancing systematic review methodology for the field of nutrition science. Furthermore, future directions for advancement, such as leveraging research recommendations better, will be explored.Support or Funding InformationUSDA