1. Gamma-Dynacare Medical Laboratories, Brampton, Ontario, Canada
2. Department of Pathology and Laboratory Medicine, The Ottawa Hospital and University of Ottawa, Ottawa, Ontario, Canada
3. Departments of Medicine and Epidemiology and Community Medicine, University of Ottawa, Ottawa, Ontario, Canada
4. Clinical Epidemiology Program, Ottawa Health Research Institute, Ottawa, Ontario, Canada
5. Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada