(P26-016-23) Systematic Reviews With Meta-Analysis To Support Federal Policy and Programs: Methods of the USDA’s Nutrition Evidence Systematic Review Branch

Objectives: Describe USDA Nutrition Evidence Systematic Review’s (NESR) methods for systematic reviews with meta-analysis (MA) to answer public health-related food and nutrition questions and support Federal policy and programs.

Methods: To develop NESR methods for systematic reviews with MA, NESR reviewed and assessed MA methodologies of leading evidence synthesis organizations and consulted experts in nutrition, evidence synthesis, and biostatistics. NESR integrated MA best-practices into NESR’s existing gold-standard methods for systematic reviews.

Results: NESR systematic reviews with MA statistically combine eligible quantitative results from individual studies. NESR analysts work with expert groups to develop an a priori protocol, which includes the rationale for including MA and planned comparisons of interest, quantitative summary measures, methods for combining data across studies, assessments of heterogeneity and non-reporting bias, sensitivity analyses and meta-regressions, as well as the plan for how MA results inform graded conclusion statements.

NESR systematic reviews with MA follow a rigorous process of systematically searching and screening the scientific literature, extracting data, and completing study design-specific risk of bias assessment for included studies. The quantitative synthesis follows the protocol and includes considerations for common study designs in nutrition research (e.g., RCTs, non-RCTs, cohort studies). Heterogeneity (e.g., I², tau²) is assessed and variation is explored with sensitivity and meta-regression analyses. When evidence is sufficient, analysts model dose-response relationships and assess non-reporting bias with funnel plots and asymmetry tests. The final report provides rationales for any post-hoc analyses conducted.

MA results are considered when developing conclusion statements and grading the strength of the evidence. MA findings may inform consistency, precision, and generalizability of results when grading conclusion statements.

Conclusions: NESR systematic reviews with MA use systematic, transparent, rigorous, and protocol-driven methods to search for, evaluate, quantitatively synthesize, and grade the strength of eligible evidence to answer questions of public health importance.

Funding Sources: USDA, Food & Nutrition Service, Center for Nutrition Policy & Promotion