1. Clinical Addiction Research and Education Unit, Section of General Internal Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
2. Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts
3. Center for Care Delivery and Outcomes Research, Minneapolis Veterans Affairs Health Care System, Minneapolis, Minnesota
4. Minneapolis Veterans Affairs Health Care System, Minneapolis, Minnesota
5. Department of Medicine, University of Minnesota Medical School, Minneapolis
6. Department of Anesthesiology, University of Michigan, Veterans Affairs Center for Clinical Management Research, Ann Arbor