1. Center for Health Services Research in Primary Care, Durham Veterans Affairs Medical Center, 508 Fulton St., Durham, NC
2. Department of Population Health Sciences, Duke University School of Medicine, Durham, NC
3. Division of General Internal Medicine, Duke University School of Medicine, Durham, NC
4. Department of Health Policy and Management, University of North Carolina at Chapel Hill, CB #7411, Chapel Hill, NC
5. Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, NC