1. Department of Family and Community Medicine, University of California, Davis, Sacramento2Center for Healthcare Research and Policy, University of California, Davis, Sacramento
2. Department of Radiology, University of Washington, Seattle4Department of Health Services, University of Washington, Seattle
3. Center for Healthcare Research and Policy, University of California, Davis, Sacramento
4. Department of Family Medicine, University of Washington, Seattle
5. Department of Medicine and Epidemiology, University of Washington, Seattle7Department of Epidemiology, University of Washington, Seattle