1. Centre for Clinical Epidemiology; Jewish General Hospital; Montreal Quebec Canada
2. Thrombosis Program; Division of Hematology; Department of Medicine; University of Ottawa; Ottawa Ontario Canada
3. Clinical Epidemiology Unit; Ottawa Hospital Research Institute; The Ottawa Hospital; Ottawa Canada
4. Division of Hematology; Department of Medicine; University of Western Ontario; London Canada
5. Department of Medicine; Dalhousie University; Halifax Nova Scotia Canada
6. Department of Medicine; Hôpital du Sacré-Coeur de Montréal; University of Montreal; Montreal Quebec Canada
7. Université de Brest; EA3878, Brest France
8. Department of Medicine; McGill University; Montreal Quebec Canada
9. Department of Medicine; Michael G. DeGroote School of Medicine; McMaster University; Hamilton Ontario Canada
10. Department of Internal Medicine; Geneva University Hospital; Geneva Switzerland
11. Department of Medicine; UC Davis School of Medicine; Sacramento California USA
12. Department of Medicine; St Paul's Hospital; University of British Columbia; Vancouver British Columbia Canada