AWM: Systematic Review and Guideline Methods (2022)

AWM: Systematic Review and Guideline Methods (2022)

The National Academy of Science describes Clinical Practice Guidelines (CPGs) as “statements that include recommendations intended to optimize patient care that are informed by a systematic review of evidence and an assessment of the benefits and harms of alternative care options.”1 The development of CPGs is guided by systematic methodology in order to introduce as little bias as possible when interpreting evidence. However, recommendations must also consider client values as well as other crucial factors (such as financial cost, feasibility of implementation, or stakeholder buy-in) when recommending practice decisions. This section outlines and details the methodology used to develop the current Evidence-Based Nutrition Practice Guideline for RDNs working with adults with overweight or obesity. The methodology for this project was developed using the process of the Academy of Nutrition and Dietetics,2,3 in accordance with the Standards for Developing Clinical Practice Guidelines from the National Academy of Science using grading and guideline development tools from the GRADE (Grading of Recommendations Assessment, Development and Evaluation) group.4,5 


The objective of this EBPG is to provide evidence-based recommendations for dietitians providing behavioral-based nutrition interventions for adults (≥18 years of age) with overweight and obesity to improve cardiometabolic outcomes, quality of life, and weight outcomes, when appropriate for and desired by the client. 

Overview of the Guideline Development Process

Evidence-based recommendations are the product of a rigorous and systematic, step-by-step process. These steps are listed and described in detail in the sections below. 

  1. Conduct a scoping review to determine literature availability;
  2. Recruit an expert panel;
  3. Determine priorities, gaps in research, and, consequently, Population-Intervention-Comparison-Outcome (PICO)-formatted systematic review research questions to support recommendations;
  4. Develop a priori eligibility criteria for the systematic review;
  5. Design a search plan and register on the PROSPERO database;
  6. Information Specialist conducts the search of databases;
  7. Titles and abstracts from database searches are screened and hand searched for relevant articles; review full-text articles for inclusion;
  8. Trained evidence analysts extract data using a standardized tool and assess quality (risk of bias) for each included article; 
  9. Study characteristics and results are summarized in tabular form and evidence for each outcome is synthesized qualitatively (evidence summary and conclusion statement), quantitatively (in meta-analyses when possible) and in tabular form (summary of findings table) for each outcome reported in the included studies. Conclusion statements are graded according to Academy and GRADE principles. 
  10. When evidence is available, expert panel members complete GRADE’s evidence-to-decision (EtD) framework to determine the best recommendations based on evidence, clinical expertise and client values.
  11. When no evidence is available from the systematic review, expert panel members used these same principles (supporting evidence outside of the systematic review, clinical expertise and patient values) to develop consensus recommendations; 
  12. Recommendations are rated according to Academy principles and voted on and approved by expert panel members;
  13. Evidence-based practice guideline is reviewed externally by thirteen individuals with content expertise using the AGREE II tool and key recommendations were posted for public comment;
  14. Authors responded to peer reviewer comments.

Supporting Systematic Review

To inform the current EBPG, the Academy’s Evidence Analysis Center (EAC) collaborated with content experts in the field of adult overweight and obesity management to conduct a systematic review examining the effect of behavior-based MNT interventions provided by dietitians. The systematic review followed methods from the Academy2 and the Cochrane Collaboration’s Grading of Recommendations Assessment, Development and Evaluation (GRADE) methods4 and adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist.6 Details of the systematic review can be found elsewhere.7,8 The primary research question addressed in the systematic review was: In adults ≥18 years of age with overweight or obesity, what is the effect of overweight and obesity management interventions provided by a dietitian, compared to usual care or no intervention, on defined outcomes? Overweight and obesity were defined as BMI ≥25 and ≥30 kg/m2, respectively, or as defined for a specific adult population (e.g., BMI ≥22 and ≥25 kg/m2, respectively, for adults who are of Asian descent). There is a paucity of intervention trials that specifically describe assessing and addressing each individual’s complex contributions to weight status and its associated outcomes. Though the panel attempted to identify trials that could inform interventions for groups with high rates of overweight or obesity or who are under-represented, few trials focused specifically on these groups.7 There is growing recognition that research on moderators of intervention outcomes is needed to understand which interventions are most effective for whom. Most current research examining interventions provided by dietitians focuses on cardiometabolic and anthropometric outcomes.9 Studies that did not include dietitians as interventionists were not included in this supporting systematic review. Panel members identified specific outcomes of interest that are frequently used in practice, modifiable, and associated with health status. These included BMI, percent weight loss, WC, BP, FBG, QoL, cost-effectiveness and adverse events. Though there is increasing focus on more client-centered outcomes such as QoL, mental health/psychological outcomes, and internalized weight bias, few studies have examined  these outcomes.9

Databases searched included MEDLINE, Embase, PsycINFO, Cochrane CENTRAL, Cochrane Database of Systematic Reviews and CINAHL for literature published between January 1, 2008, and January 25, 2021, in the English language. The search included a combination of terms for overweight or obesity and lifestyle, behavioral or diet interventions for adults. The full search strategy can be found elsewhere.7,8 Sixty-seven randomized controlled trials (RCTs) and three non-RCTs (represented in 83 articles) were included and analyzed to inform the current EBPG.10-92 A full description of the included studies can be found elsewhere.7,8 Effect sizes, conclusion statements and grades for certainty (quality) of evidence from the systematic review can be found in the Summary of Findings Table. Certainty of evidence was graded according to the GRADE method, which includes consideration of risk of bias of the included studies, inconsistency between studies, indirectness, imprecision and other factors.4 Results from the systematic review are described in recommendation narratives. For topics not addressed by the supporting systematic review, such as weight bias, recent external systematic reviews and expert opinions were used to inform practice recommendations.  

Guideline Development Process

This EBPG was conducted using Academy methods3 and GRADE’s Evidence-to-Decision (EtD) framework.93,94 Each potential recommendation statement and supporting text was drafted by two expert panel members based on results from the systematic review7 interpreted through GRADE’s EtD framework.93,94 The EtD framework guided expert panel members to consider the following factors when drafting potential recommendations: supporting evidence including the balance of benefits and harms, evidence certainty, and importance of affected outcomes; resource use; equity; client values; acceptability and feasibility to stakeholders and clinical expertise. After the two frameworks were completed independently, information was synthesized by the methodologist and thoroughly reviewed and edited by all EBPG team members. Final recommendation statements were approved by expert panel member voting. Due to the demonstrated improvement of all outcomes considered and few adverse events identified, the expert panel generally considered overweight and obesity management interventions to have more benefits, including to QoL, than harms. 

Grading of Recommendation Statements

Recommendation statements are graded with a number (1 or 2) and a letter (A-D). The letter refers to the strength of evidence from the supporting systematic review (HIGH-A, MODERATE-B, LOW-C or VERY LOW-D).4 When multiple outcomes with different evidence ratings were considered for a recommendation statement, or when recommendations were supported by sub-analyses that were not specifically graded on a summary of findings table, the team prioritized included outcomes and used definitions of evidence grades to guide grading of the recommendation statement (Grading Definitions Table).4 The number in the recommendation rating refers to the strength of the recommendation. Typically, higher certainty evidence results in strong recommendations and lower certainty evidence results in weak recommendations. However, in some cases, evidence was limited but expert panel members came to the consensus that a recommendation should be rated as strong due to clinical experience. In cases in which evidence was unavailable or unclear, recommendations were graded as “Consensus” and were based on relevant literature, scope of practice, and clinical expertise. Recommendation statements include the terms “recommend/should” for strong recommendations, “suggest/may” for weak recommendations, and “it is reasonable” for consensus recommendations. The Relationships between Recommendations and Evidence Table  describes the relationships between the recommendation statements and supporting evidence. 

Stakeholder Involvement & External Review

This EBPG and its supporting systematic review were written by a team of dietitians. From candidates who responded to recruitment requests by submitting their applications, six expert panel members with practice and/or research expertise in providing nutrition interventions for adults with overweight or obesity were selected by the Academy’s Council on Research’s Work Group Selection Subcommittee, which is composed of Academy members. Three additional dietitians served as systematic review and EBPG methodologists. One of the dietitians was a licensed clinical psychologist and one was an American College of Sports Medicine Certified Exercise Physiologist. The full EBPG team of nine dietitians participated in formulating research questions and conducting the systematic review. Expert panel members used expertise and evidence to guide the content of recommendations and unanimously approved recommendation statements and ratings. This EBPG underwent peer review. Specifically, 11 external reviewers working in the field of adult overweight and obesity management were recruited to review all recommendations and supporting information. These 11 reviewers utilized the Appraisal of Guidelines for Research Evaluation II (AGREE II) tool95  to determine the rigor of EBPG development and were also invited to give feedback on the content of the recommendations and supporting information. Following revisions from the peer review and public comment, the guideline was again reviewed by 13 peer reviewers, including the original peer reviewers, with content expertise to examine updates and provide any additional major suggestions.

This EBPG also underwent a “public comment” period. Specifically, stakeholders, including adults affected by overweight or obesity, were invited to review key recommendation statements and answer questions about key recommendations which were posted on a public website. Stakeholders were asked to respond to questions adapted from the National Institute for Health and Care Excellence.96 Public stakeholder comments were reviewed and major themes were identified by the  EBPG team. The EBPG team then conducted an extensive update of the EBPG to address concerns identified during the public comment period, which included placing greater emphasis on individualized care, recognizing and addressing inclusion, diversity, equity and access (IDEA), weight bias and stigma, clarifying specific groups to which specific recommendations may or may not apply, and placing greater emphasis on the challenges of dietary adherence and weight loss maintenance. Any recommendation statements changed during the review process were voted on and approved by expert panel members.

This EBPG team consulted the literature for qualitative or quantitative studies that examined client perspectives regarding overweight and obesity management interventions. Findings from these studies informed recommendations and implementation considerations.97-100

Finally, this guideline as well as author responses to reviewer comments were approved by the Council on Research at the Academy of Nutrition and Dietetics, a committee of nutrition research leaders who are members and provide strategic direction for Academy research.101 

Monitoring, Evaluating and Auditing Guideline Implementation

The evidence-based cycle extends beyond creating evidence-based practice recommendations. Ideally, recommendations are implemented into practice, evaluated for efficacy, and updated accordingly. At the Academy, implementation research may be conducted by the Nutrition Research Network.102 Dietitians can contribute to research examining implementation and evaluation of recommendations by participating in Nutrition Research Network studies, including by providing client data in the Academy of Nutrition and Dietetics Health Informatics Infrastructure (ANDHII) program.103 When determining which recommendation to prioritize for implementation, RDNs are encouraged to prioritize recommendations that will have the greatest impact for their specific circumstances and clients.104 

Guideline Updates

Academy EBPGs are considered for update every five years. At that point, a scoping review is conducted to determine whether substantial literature on the topic has been published since the past systematic review. The Academy’s Council on Research, informed by the research team, determines whether this EBPG requires modification to all, some, or none of the recommendation statements.


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