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Sunnybrook Research Institute

William Geerts, MD

Senior Scientist

Sunnybrook Health Sciences Centre
2075 Bayview Ave., Room D6 74
Toronto, ON
M4N 3M5

Phone: 416-480-4427
Fax: 416-480-4186

Administrative Assistant: Alison Fairclough
Phone: 416-480-4427


  • B.Sc., 1975, Biology, McMaster University, Canada
  • B.Med.Sci., 1977, Medicine, Memorial University of Newfoundland, Canada
  • MD, 1979, Medicine, Memorial University of Newfoundland, Canada

Appointments and Affiliations:

Research Foci:

  • Epidemiology, prevention and treatment of thromboembolic disorders
  • Quality of care and patient safety in thromboembolism

Research Summary:

Over the past 25 years, Dr. Geerts has developed and participated in clinical research in all aspects of thromboembolism, including epidemiology, diagnosis, treatment and prevention. His primary interest has been in the prevention of venous thromboembolism (VTE) in high-risk patients, especially following trauma. He has performed the most comprehensive, prospective study of the risks of venous thromboembolism in trauma patients and found that they are the highest-risk group for thromboembolism in hospitals.

Subsequently, Dr. Geerts and his group conducted the first large randomized trial of thromboprophylaxis in major trauma patients, by comparing subcutaneous low-dose heparin with low molecular weight heparin in a double-blinded manner. This study demonstrated that the early use of low molecular weight heparin is more efficacious than low-dose heparin in trauma patients without increasing bleeding.

His current research interests extend to the implementation of knowledge about thromboembolism into clinical practice.

Selected Publications:

See current publications list at PubMed.

  1. Sud S, Mittman N, Cook DJ, Geerts W, Chan B, Dodek P, et al. Screening and prevention of venous thromboembolism in critically ill patients: a decision analysis and economic evaluation. Am J Respir Crit Care Med. 2011 Dec; 184(11):1289–1298.
  2. Geerts W. Prevention of venous thromboembolism: a key patient safety priority. J Thromb Haemost. 2009 Jul; 7(Suppl 1):1–8.
  3. Selby R, Geerts W, Ofosu FA, Craven S, Dewar L, Phillips A, Szalai JP. Hypercoagulability after trauma: Hemostatic changes and relationship to venous thromboembolism. Thromb Res. 2009 Jul; 124:281–287.
  4. Eriksson BI, Borris LC, Friedman RJ, Haas S, Huisman MV, Kakkar AK, Bandel TJ, Beckmann H, Muehlhofer E, Misselwitz F, Geerts W, for the RECORD1 Study Group. Rivaroxaban versus enoxaparin for thromboprophylaxis after hip arthroplasty. N Engl J Med. 2008 Jun; 358:2765–2775. 
  5. Geerts WH, Bergqvist D, Pineo GF, Heit JA, Samama CM, Lassen MR, Colwell CW. Prevention of venous thromboembolism. American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest. 2008 Jun; 133(6 Supp):381S–453S.

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