1. Center for Health Services Research in Primary Care, Durham Veterans Affairs Medical Center, Durham, North Carolina2Division of General Internal Medicine, Department of Medicine, Duke University, Durham, North Carolina
2. Group Health Research Institute, Seattle, Washington4Division of General Internal Medicine, Department of Medicine, University of Washington, Seattle
3. Center for Health Services Research in Primary Care, Durham Veterans Affairs Medical Center, Durham, North Carolina
4. Veterans Administration North Texas Health Care System, Dallas, Texas6Division of Gastrointestinal and Endocrine Surgery, University of Texas Southwestern Medical Center, Dallas7Division of General Surgery, Northwestern University, Chicago, Illinois8Deputy Editor, JAMA
5. Center for Health Services Research in Primary Care, Durham Veterans Affairs Medical Center, Durham, North Carolina9Department of Biostatistics and Bioinformatics, Duke University, Durham, North Carolina