1. Northwest Institute of Acupuncture and Oriental Medicine, Seattle, WA; Department of Epidemiology, University of Washington, Seattle, WA and Center for Health Studies, Group Health Cooperative, Seattle, WA
2. Center for Health Studies, Group Health Cooperative, Seattle, WA and Departments of Family Medicine and Health Services, University of Washington, Seattle, WA
3. Northwest Institute of Acupuncture and Oriental Medicine, Seattle, WA and Department of Epidemiology and Biostatistics, University of California - San Francisco, San Francisco, CA