| Systematic Review Step | Examples | ||
|---|---|---|---|
| Vitamin D and Bone Health (10) | Soy and Health Outcomes (12) | (N-3) Fatty Acids and Arrhythmogenic Mechanisms (13) | |
| Form multidisciplinary research team (in addition to systematic review methodologists and systematic review sponsors) | Domain experts in nutrition, endocrinology, pediatrics, and biochemistry | Domain experts in soy research and relevant health areas | Domain experts in (n-3) fatty acids research and cardiac electrogenesis and arrhythmia outcomes |
| Develop analytic framework | Related intakes, serum 25(OH)D, active form (1,25(OH)D) and bone health | Not available | Different for whole animal, intact animal isolated organ and cell, and cell culture studies |
| Develop and refine key questions | Serum 25(OH)D and bone health Intake or sun exposures and serum 25(OH)D Vitamin D intakes and BMD, fractures or falls; variation with age, ethnicity, geography, BMI Sunlight and 25(OH)D without ↑ skin cancer Intakes related to toxicities | Soy formulations, doses, and purposes in
trials Whole soy or soy constituents and heath outcomes Dose-response of soy forms or constitutions Frequency and type of adverse effects Dose-response of whole soy and constituents on safety | Evidence from whole animal studies that (n-3)
fatty acids affect arrhythmogenic outcomes Evidence from cell culture and tissue studies that (n-3) fatty acids directly affect cell organelles involved in electrogenesis |
| Define eligibility criteria | Some questions limited to RCTs Some questions included prospective cohorts, case-control and before-after studies. One question restricted to existing systematic reviews Included studies that assessed vitamin D2 or D3 with or without calcium supplementation Excluded studies that used calcium with vitamin D as a control arm unless a placebo was available as a comparator; vitamin D preparations calcitriol or alphacalcidol; studies on the efficacy of vitamin D for the treatment of secondary causes of osteoporosis or for treatment of vitamin D-dependent rickets | Inclusions: subjects ≥ 13 y; RCTs, cohorts,
cross-over and non-randomized comparison studies; ≥5
subjects in soy arm; any health condition; quantification of
soy intake; outcomes of interest;. ≥ 4 wk
duration Exclusions: soy mixed with other ingredients; soy enteral feedings; reviews; non-trial observational studies; animal or in vitro studies; ingested soy not quantified; insignificant amounts of soy; no intake data | Inclusions: experiments of (n-3) fatty acids
and arrhythmia, intermediate mechanisms of arrhythmia, and
electrogenesis Exclusions: letters or abstracts; mechanisms related to eicosanoids, enzymes, receptors, membrane composition, fluidity, or phospholipids; non-mammalian animals or cell lines; no relevant outcomes; no (n-3) fatty acids intervention; reviews; safety assessments |
| Identify search terms and strategy | 130 key terms | 33–63 key terms per search | 64 search terms |
| Screen abstracts according to eligibility criteria | 6566 unique records | ~ 4800 abstracts | 1807 abstracts |
| Articles retrieved for evaluation | 1447 reports | 599 full text articles | 274 articles |
| Extract data from articles which met inclusion criteria | 167 articles | 178 articles | 89 articles |
| Construct evidence and summary tables | 18 summary tables | 86 summary tables | 31 summary tables |
| Assess methodological quality, applicability | Jadad scale for RCT Good, fair, or consistent rating for observational studies | 3-categories (A,B,C) of methodological
quality 3-category applicability grade | 4-categories for fatty acid and/or level of fat in the comparison diet |
| Perform meta-analyses, as appropriate | Meta-analysis of RCTs that assessed interventions, populations and outcomes | Meta analysis for several cardiovascular
outcomes Meta-regression of differences across studies and dose-responses | Meta analyses for whole animal
studies For isolated organ and cell studies, qualitative data summary |
| Synthesize results, write report, have report reviewed | Report written by EPC; peer review by TEP members and external reviewers | Report written by EPC; peer review by TEP members and external reviewers | Report written by EPC; peer review by TEP members and external reviewers |
EPC, Evidence-based Practice Center; FA, fatty acid; RCT, randomized controlled trial; TEP, technical expert panel
From: 1, Introduction
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