Evaluating the Process to Develop the Dietary Guidelines for Americans, 2020-2025 A Midcourse Report (2022) / Chapter Skim
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3 Analysis of the Scientific Methodologies, Review Protocols, and Evaluation Processes of the Dietary Guidelines
3 Analysis of the Scientific Methodologies, Review Protocols, and Evaluation Processes of the Dietary Guidelines
Pages 39-82
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From page 39... ...
. The committee was asked specifically to respond to the question: How did the process used to develop the Dietary Guidelines for Americans, 2020–2025, including scientific methodologies, review protocols, and evaluation processes, compare to the seven recommendations in the 2017 National Academies report?
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The 2017 National Academies report was preceded by the report Optimizing the Process for Establishing the Dietary Guidelines for Americans: The Selection Process (NASEM, 2017b)
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and, if adopted, time for deliberative planning, budgeting, and staffing to support implementation. Thus, in its analysis of the DGA process, the committee gave consideration to the fact that full implementation of the 2017 National Academies recommendations would occur over the course of subsequent DGA cycles.
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Dietary Guidelines Planning and Continuity Group to monitor and curate evidence generation, to identify and prioritize topics for inclusion in the DGA, and to provide strategic planning support across DGA cycles; b. Technical expert panels to provide content and methodological consulta tion during evaluation of the evidence; and c.
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• Oversee monitoring of new evidence Technical expert panels • Help NEL refine key questions, prioritize (TEPs) questions, and establish PICO criteria about a Systematic reviews specific topic (e.g., P/B-24, CVD)
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project; however, the systematic reviews conducted by the 2020 DGAC were initiated after the release of the 2017 National Academies report.3 Improvements in how the members of the DGAC would be selected and appointed to minimize conflicts of interest, expand input, and improve transparency had been requested in 2017 so the input could be incorporated into the process to develop the 2020– 2025 DGA. The remaining recommended changes were not required to be implemented in 2017, which suggests that the federal agencies knew that they probably could not incorporate the recommendations during that DGA cycle; nevertheless, they would be useful for future planning.
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Topic Identification and P/B-24 projects, as well as those from prior DGA cycles that were relevant to other life stages (Raiten et al., 2014; Stoody et al., 2019)
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The 2020 DGAC Scientific Report supported use of a "continuous model to identify and evaluate evidence as it is published" (DGAC, 2020)
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. The report also envisioned that the DGSAC would integrate all data inputs (which could have come from food pattern modeling or new approaches to data analysis as well as from the systematic reviews prepared by NESR)
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The 2017 National Academies report proposed that TEPs could assist with developing the systematic reviews by, for example, "operationaliz[ing] the research questions formulated by the DGPCG by helping to set the eli
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Conclusions for Recommendation 1 The committee concluded that prioritization of the topics for systematic reviews used in the 2020 DGA cycle was completed by federal staff, with input from public comments, before the DGAC began its deliberations. The committee concluded that, although the response by USDA and HHS to recommendation 1 is understandable under the circumstances related to the timing of the recommendation and resource constraints, it may have been possible to create greater differentiation between the roles of NESR and the DGAC.
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. This recommendation specifically focused on transparency when the 2020 DGAC Scientific Report and 2020–2025 DGA differ, as well as when USDA and HHS describe whether and why the DGA recommendations were different.
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methylmercury and higher in omega-3 fatty acids NOTES: DGA = Dietary Guidelines for Americans; DGAC = Dietary Guidelines Advisory Committee. Further information in Appendix D
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In its assessment of the first three questions, the committee looked to the public record to determine whether USDA and HHS provided a clear explanation for why the 2020–2025 DGA differed from the 2020 DGAC Scientific Report on the added sugars and alcohol recommendations. The following USDA and HHS response (DGA, n.d.-b)
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Assessment of Recommendation 3 Background The 2017 National Academies report recommended separating the roles of the USDA NEL staff and the DGSAC (see Box 3-4, recommendation 3) as a way to ensure that the process used by the NESR, formerly called NEL, follows best practice principles and a rigorous approach to the conduct of systematic reviews (NASEM, 2017a)
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such that a. The NEL staff plan and conduct systematic reviews with input from tech nical expert panels, perform risk-of-bias assessment of individual studies, and assist the DGSAC as needed; b.
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. To conduct the resulting systematic reviews, the NEL developed several Technical Expert Collaboratives (TECs)
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The committee's review of evidence showed that for systematic reviews completed after release of 2017 National Academies report, a process for internal federal peer review was developed and coordinated by the co-executive secretary for the DGAC from USDA's Agricultural Research Service (ARS)
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As noted in the 2017 National Academies report, the TEPs were8 expected to review and provide feedback to NESR to refine the systematic review materials. The DGAC was responsible for establishing protocols, synthesizing and grading evidence, and drafting conclusions in its systematic reviews.
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For systematic reviews conducted after the release of 2017 National Academies report, NESR systematic reviews were reviewed internally to the federal government (by HHS, USDA, Department of Defense, and Department of Veteran Affairs) and the results were posted on the USDA website.
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systematic reviews underpins the strength of DGA recommendations. The 2017 National Academies report further states that "the NEL process for conducting original systematic reviews is thorough but has not been updated to reflect recent advances in systematic review methodology" (NASEM, 2017a, p.
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Analytical tools are used to characterize risk of bias for specific types of research. Outcome reporting bias may be important to address in policy-related systematic reviews.
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a The title of this table was modified after release of a prepublication version of the report to the sponsor to clarify that the table is the committee's compilation of identified systematic review practices and that the list is not comprehensive. the already thorough NESR systematic reviews remain up to date, the committee's assessment highlighted only those items where there were differences between NESR's processes and committee-identified practices (see Appendix E)
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. The committee compared the NESR processes to those used by leading organizations, which are described here as "committee-identified practices." The committee also compared NESR systematic review practices from the cycles to develop the 2015–2020 and 2020–2025 DGA to determine if the changes made to the process align more closely with committee-identified practices as recommended in the 2017 National Academies report (see Appendix F)
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The committee reviewed the processes used by NESR staff to incorporate input received from these experts. The details of the NESR CQA program, as described on the NESR website, identify the 2017 National Academies reports in their external review by experts.11 In addition, NESR has a long-standing, robust afteraction analysis that is informed by participants in the systematic review process.
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. However, there are still some important differences (e.g., peer review, management of systematic review protocols, processes for updating existing systematic reviews, and description of process for committee deliberations)
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population, including those who are healthy and/or those at risk of chronic disease." Peer review Risk-of-bias tools updated Implementation of DistillerSR, a systematic review tool Topics identified by USDA and HHS versus DGAC Additional detail provided on roles of NESR and DGAC More details regarding description of use of GRADE tools used to assess certainty of evidence Addition of second analyst to review and verify data and process to resolve conflicts Changes Under Consideration Ongoing interest in evidence surveillance Ongoing interest in how to incorporate meta-analysis Enhanced food pattern modeling Systems thinking and modeling NOTES: DGA = Dietary Guidelines for Americans; DGAC = Dietary Guidelines Advisory Committee; GRADE = Grading of Recommendations Assessment, Development and Evaluation; HHS = U.S. Department of Health and Human Services; NESR = Nutrition Evidence Systematic Review; PICO = population, intervention/exposure, comparator, and outcome of interest; USDA = U.S.
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Although the committee was unable to assess the implementation of the effectiveness of the training fully, outcomes from the CQA, and benefits of collaboration with other experts and investments in technology, indicate that the NESR practices included recent improvements. Notably, there are opportunities to enhance the transparency and, thus, the perceived integrity of the systematic review through external peer review as well as improved management of systematic review protocols (including more clearly defined processes for updating existing systematic reviews and fully describing the process for creating DGAC recommendations)
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Depart ment of Health and Human Services should enhance food pattern modeling to better reflect the complex interactions involved, variability in intakes, and range of possible healthful diets. The 2017 National Academies report noted that food pattern modeling has focused on representing the overall population using population energy and nutrient requirements, typical food choices, a traditional set of food groups, and that its applicability to individuals who follow a different consumption pattern has been limited (NASEM, 2017a)
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The 2020 DGAC Scientific Report identified assumptions, strengths, and limitations of food pattern modeling. The 2020 DGAC Scientific Report indicated the food pattern modeling was based on profiles of nutrientdense foods and U.S.
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. The 2020 DGAC Scientific Report noted that, although the USDA food patterns do not address cultural variations in intake patterns, they do offer flexibility for tailoring to cultural and taste preferences (DGAC, 2020)
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For the second and third questions, the committee found that, using the traditional modeling approach, refinements were made to account for variability in intakes. The committee further found that the 2020 DGAC Scientific Report stated that the need to add or modify the USDA food patterns was explored based on systematic reviews (DGAC, 2020)
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. Specifically, the 2017 National Academies report identified the need to improve "the accuracy and efficiency of data analyses … by standardizing and validating the processes used, both within and between DGA cycles to identify nutrients of concern" (NASEM, 2017a, p.
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was proposed instead of the term nutrients to incorporate non-nutrient food components, such as fiber, and be more consistent with the 2017 National Academies report definition of non-nutritive food substances. The paper further proposed the phrase NFCs of public health
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FIGURE 3-1 Nutrient of concern decision tree framework. NOTE: DRI = Dietary Reference Intake; NFC = nutrient and food component.
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. The evaluation of dietary intake data included examinations of means and distributions of the usual intake of energy, macronutrients, and other selected food components.
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. Before convening the 2020 DGAC, federal staff documented and refined the process for identifying nutrients of public health concern and initiated discussions regarding data analyses, including those specific to pregnancy and lactation (see Appendix B-5)
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For the first question, the committee found that the 2020 DGAC Scientific Report and a later peer-reviewed publication documented a framework that standardized the terminology, thresholds, analytic methods, and interpretation related to nutrients and food components of public health relevance (Bailey et al., 2021; DGAC, 2020)
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. Conclusions for Recommendation 6 The 2020 DGAC Scientific Report documented and published a peerreviewed framework standardizing the terminology, thresholds, analytic methods, and interpretation related to nutrients of concern, building on the approach used by the 2015 DGAC and proposing an approach for future committees.
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. Although the 2020 DGAC Scientific Report notes that HHS and USDA have enacted many of the 2017 National Academies recommendations, it also acknowledged a lack of progress on the systems science recommendation, and thus encouraged further work:
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(see Appendix B-5) The 2020 DGAC Scientific Report recognized the ambitious nature of the goals laid out in recommendation 7, noting that there will be a need to draw on broader scientific expertise: "The nature of the recommendation acknowledges that moving to incorporate systems thinking will require different types of scientific expertise outside of nutrition and food science to evaluate diet and health relations in a broader body of evidence" (Schneeman et al., 2021, p.
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. Additionally, the agencies stated that "agencies adopt new methodologies when they are advanced enough to support national nutrition public health guidance," which was done when they adopted food pattern modeling into the 2005 DGAC (see Appendix B5)
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2021. Cochrane handbook for systematic reviews of interventions version 6.2.
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2019. The pregnancy and birth to 24 months project: A series of systematic reviews on diet and health.
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