Abstract

Nutrient reference values have significant public health and policy implications. Given the importance of defining reliable nutrient reference values, there is a need for an explicit, objective, and transparent process to set these values. The Tufts Medical Center Evidence-based Practice Center assembled a group of nutrition experts from academic institutions and federal government agencies, led participants in discussions, conducted exercises in formulating questions and evidence review criteria that would be amenable to systematic reviews of the scientific literature, performed a literature search on the questions to identify potentially relevant publications, and identified challenges and limitations of applying this method to support the development of nutrient reference values, using vitamin A as an example. The workgroup concluded that the systematic review approach could be productively used to inform the development of reference values. Challenges identified in this exercise include prioritizing and defining research questions when the volume of literature is large, relying on intermediate (surrogate) outcomes when few or no studies directly linked nutrient intake with clinical outcomes are available, and determining reliable nutrient biomarkers. Ultimately, an objective, unbiased systematic review of a defined question could be useful; not only in helping to set nutrient reference values, but also for increasing the transparency of the decision making process.

systematic review, evidence-based, diet, nutrition recommendations, nutrition guidelines.

Contents

• Preface
• Nutritional Systematic Reviews
• 1. Introduction
  • Organizations Conducting Systematic Reviews in Nutrition
  • Impetus for the Current Report
• 2. Systematic Review Methods
  • Overview
• 3. Integrating Systematic Review Into a Process to Establish Nutrient Reference Values
  • Generic Analytic Framework for Nutrient Reference Values
  • Decision-making for Questions and Outcomes of Interest
• 4. Workgroup Exercise
  • Activities Surrounding the First Meeting
  • Activities Surrounding the Second Meeting
  • Analytic Framework for Vitamin A Reference Value
  • Evidence Map for Key Questions on Vitamin A Reference Values
• 5. Summary
  • Conclusions
• Acronyms
• Glossary
• Workshop Participants
• References

Prepared for: Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services.¹ Contract No. 290-02-0022. Prepared by: Tufts Evidence-based Practice Center, Boston, MA.

Suggested citation:

Russell R, Chung M, Balk EM, Atkinson S, Giovannucci EL, Ip S, Lichtenstein AH, Taylor Mayne S, Raman G, Ross AC, Trikalinos T, West KP Jr, Lau J. Issues and Challenges in Conducting Systematic Reviews to Support Development of Nutrient Reference Values: Workshop Summary. (Prepared by the Tufts Evidence-based Practice Center under Contract No. 290-02-0022). AHRQ Publication No. 09-0026-2. Rockville, MD: Agency for Healthcare Research and Quality. March 2009.

This report is based on research conducted by the Tufts Evidence-based Practice Center (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD (Contract No. 290-02-0022). The findings and conclusions in this document are those of the author(s), who are responsible for its content, and do not necessarily represent the views of AHRQ. No statement in this report should be construed as an official position of AHRQ or of the U.S. Department of Health and Human Services.

The information in this report is intended to help clinicians, employers, policymakers, and others make informed decisions about the provision of health care services. This report is intended as a reference and not as a substitute for clinical judgment.

This report may be used, in whole or in part, as the basis for the development of clinical practice guidelines and other quality enhancement tools, or as a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied.

No investigators have any affiliations or financial involvement (e.g., employment, consultancies, honoraria, stock options, expert testimony, grants or patents received or pending, or royalties) that conflict with material presented in this report.

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