Structured Abstract

Contents

• Preface
• Acknowledgments
• Workgroup Members
• Peer Reviewers
• Introduction
  • Empirical Assessments of Risk of Bias
  • Need for a Revised Approach to Evaluating Observational Studies
  • Earlier Phases of Development
  • Project Objectives
• Methods
• Results
  • Expand the Analytic Framework To Consider Sources of Confounding
  • Identify the Source of Bias and Confounding Specific to Each Included Design
  • Assess Individual Studies for Risk of Bias and Potential Confounders
  • Consider Competing Hypotheses for Observational Studies
• Discussion
  • Recommendations for Future Methods Development
• References
• Appendix A Approaches to Assessing the Risk of Bias in Studies
• Appendix B Taxonomy on Study Design
• Appendix C Item Bank for Assessing Risk of Bias and Confounding for Observational Studies of Interventions or Exposures

Prepared for: Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services¹, Contract No. 290-2007-10056-I. Prepared by: RTI International–University of North Carolina at Chapel Hill Evidence-based Practice Center, Research Triangle Park, NC, University of Alberta Evidence-based Practice Center, Edmonton, Canada

Suggested citation:

Viswanathan M, Berkman ND, Dryden DM, Hartling L. Assessing Risk of Bias and Confounding in Observational Studies of Interventions or Exposures: Further Development of the RTI Item Bank. Methods Research Report. (Prepared by RTI–UNC Evidence-based Practice Center under Contract No. 290-2007-10056-I). AHRQ Publication No. 13-EHC106-EF. Rockville, MD: Agency for Healthcare Research and Quality; August 2013. www.effectivehealthcare.ahrq.gov/reports/final.cfm.

This report is based on research conducted by the RTI–UNC Evidence-based Practice Center, (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD (Contract No. 290-2007-10056-I). The findings and conclusions in this document are those of the authors, who are responsible for its contents; the findings and conclusions do not necessarily represent the views of AHRQ. Therefore, 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 health care decisionmakers—patients and clinicians, health system leaders, and policymakers, among others—make well informed decisions and thereby improve the quality of health care services. This report is not intended to be a substitute for the application of clinical judgment. Anyone who makes decisions concerning the provision of clinical care should consider this report in the same way as any medical reference and in conjunction with all other pertinent information, i.e., in the context of available resources and circumstances presented by individual patients.

This report may be used, in whole or in part, as the basis for 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.

None of the investigators have any affiliations or financial involvement that conflicts with material presented in this report.

1

540 Gaither Road, Rockville, MD 20850; www​.ahrq.gov