1. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
2. Division of Research, Kaiser Permanente, Oakland, California, USA
3. Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
4. Department of Medicine, University of Washington School of Medicine, Seattle, Washington
5. Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
6. Southern Alberta Clinic, Calgary, Alberta, Canada
7. Kaiser Permanente Mid-Atlantic Permanente Research Institute, Rockville, Maryland
8. Department of Medicine, University of California, San Diego, San Diego, California, USA
9. Department of Medicine, University of Toronto
10. Maple Leaf Medical Clinic, Toronto, Ontario, Canada
11. Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
12. Department of Medicine
13. Department of Pediatrics, Johns Hopkins Medicine, Baltimore, Maryland, USA.