1. Department of Health Services, University of Washington, Seattle, WA, USA
2. Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
3. Harborview Injury Prevention and Research Center, Seattle, WA, USA
4. Institute for Work and Health, Toronto, Ontario, Canada
5. Canadian Memorial Chiropractic College, Toronto, Ontario, Canada
6. Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
7. Washington State Department of Labor and Industries, Tumwater, WA, USA
8. Department of Neurology, University of Washington, Seattle, WA, USA