1. Primary Care Research Center, Division of General Internal Medicine, San Francisco General Hospital, Department of Medicine, and Institute for Health Policy Studies, University of California, San Francisco, California.
2. Department of Medicine, Division of General Internal Medicine and the Medical Effectiveness Center for Diverse Populations, San Francisco, California.
3. Cancer Center, University of California, San Francisco, California.
4. Departments of Surgery and Radiology, University of California, San Francisco, California.