1. Group Health Research Institute, Seattle, Washington2Department of Health Services, University of Washington, Seattle3Department of Family Medicine, University of Washington, Seattle
2. Group Health Research Institute, Seattle, Washington4Department of Epidemiology, University of Washington, Seattle
3. Group Health Research Institute, Seattle, Washington
4. Group Health Research Institute, Seattle, Washington5Department of Biostatistics, University of Washington, Seattle
5. Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle7Department of Rehabilitation Medicine, University of Washington, Seattle