1. Center for Health Care Evaluation, VA Palo Alto Healthcare System, and Stanford University, Palo Alto, California.
2. School of Public Health, Boston University, Boston, Massachusetts.
3. Center for Health Quality, Outcomes and Economic Research, VA Medical Center, Bedford, Massachusetts.
4. Section of General Internal Medicine, Evans Department of Medicine, Boston Medical Center.
5. Section of General Internal Medicine, and Women's Health Unit, Evans Department of Medicine, Boston Medical Center.
6. Boston University, Boston, Massachusetts.