David R. Anderson, MD; Michael J. Dunbar, MD; Eric R. Bohm, MD; Etienne Belzile, MD; Susan R. Kahn, MD; David Zukor, MD; William Fisher, MD; Wade Gofton, MD; Peter Gross, MD; Stephane Pelet, MD; Mark Crowther, MD; Steven MacDonald, MD; Paul Kim, MD; Susan Pleasance, BScN; Nicki Davis, BSc; Pantelis Andreou, PhD; Philip Wells, MD; Michael Kovacs, MD; Marc A. Rodger, MD; Tim Ramsay, PhD; Marc Carrier, MD; Pascal-Andre Vendittoli, MD
Note: All authors had full access to the study data. Dr. Anderson takes full responsibility for the integrity of the data and the accuracy of the data analysis.
Acknowledgment: The authors thank the members of the EPCAT study group (see the ).
Financial Support: By grant MCT-82948 from the Canadian Institutes for Health Research and by Pfizer Pharmaceuticals Canada. In-kind support was provided by Bayer HealthCare. Dr. Kahn is a recipient of a National Research Scholar Award from the Fonds de la Recherche en Santé du Québec.
Potential Conflicts of Interest: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M12-2191.
Reproducible Research Statement: Study protocol, statistical code, and data set: For details, contact Dr. Anderson (firstname.lastname@example.org).
Corresponding Author: David Anderson, MD, Department of Medicine, Capital Health, 1276 South Park Street, Room 442, Bethune Building, VG Site, Halifax, Nova Scotia B3H 2Y9, Canada; e-mail, email@example.com.
Current Author Addresses: Dr. Anderson: Department of Medicine, Capital Health, 1276 South Park Street, Room 442, Bethune Building, VG Site, Halifax, Nova Scotia B3H 2Y9, Canada.
Dr. Dunbar: Queen Elizabeth II Health Sciences Centre, Suite 4822, Halifax Infirmary, 1796 Summer Street, Halifax, Nova Scotia B3H 3A7, Canada.
Dr. Bohm: Concordia Joint Replacement Group, Suite 300–1155, Concordia Avenue, Winnipeg, Manitoba R2K 2M9, Canada.
Dr. Belzile: Centre Hospitalier Universitaire Québec, Pavillon Hotel Dieu de Québec, Service de Chirurgie Orthopedique, 11 Côte du Palais, Québec, Québec G1R 2J6, Canada.
Dr. Kahn: Centre for Clinical Epidemiology and Community Studies, Jewish General Hospital, 5790 Côte-des-Neiges, Room H-485, Montréal, Québec H3S 1Y9, Canada.
Dr. Zukor: Department of Orthopedics, SMBD Jewish General Hospital, 3755 Chemin de la Côte Ste-Catherine, Montréal, Québec H3T 1E2, Canada.
Dr. Fisher: McGill University Health Centre, 1650 Cedar Avenue, B5.158.7, Montréal, Québec, H3G 1A4, Canada.
Dr. Gofton: Ottawa Hospital Civic Campus, Suite J153, 1053 Carling Avenue, Ottawa, Ontario K1Y 4E9, Canada.
Dr. Gross: TaARI, David Braley CVSRI-5th Floor, 247 Barton Street East, Hamilton, Ontario L8L 2X2, Canada.
Dr. Pelet: Departement d’orthopedie, CHA-Pavillon Enfant-Jesus, 1401, 18eme Rue, Québec, Québec G1J 1Z4, Canada.
Dr. Crowther: Room L-301, St Joseph's Hospital, 50 Charlton Avenue East, Hamilton, Ontario L8N 4A6, Canada.
Dr. MacDonald: London Health Sciences Centre, University Hospital, 339 Windermere Road, London, Ontario N6A 5A5, Canada.
Dr. Kim: Ottawa Hospital General Campus, 501 Smyth Road, Room W1650, Box 502, Ottawa, Ontario K1H 8L6, Canada.
Ms. Pleasance: Queen Elizabeth II Health Sciences Centre, Capital Health Centre for Clinical Research, 5790 University Avenue, Room 132, Halifax, Nova Scotia B2H 1V7, Canada.
Ms. Davis: 21 Robertson Avenue, Gander, Newfoundland A1V 1Y1, Canada.
Dr. Andreou: Department of Community Health and Epidemiology, Dalhousie University, 5790 University Avenue, Room 414, Halifax, Nova Scotia B3H 1V7, Canada.
Dr. Wells: Ottawa Hospital General Campus, LM 12 Box 206, 501 Smyth Road, Ottawa, Ontario K1H 8L6, Canada.
Dr. Kovacs: Victoria Hospital, 800 Commissioners Road East, Room A2-401, London, Ontario N6A 4G5, Canada.
Dr. Rodger: Ottawa Hospital General Campus, 501 Smyth Road, W6120, Box 201, Ottawa, Ontario K1H 8L6, Canada.
Dr. Ramsay: Ottawa Hospital General Campus, Box 201b, 501 Smyth Road, Ottawa K1H 4E9, Canada.
Dr. Carrier: Division of Hematology and CEP, Ottawa Hospital General Campus, 501 Smyth Road, Box 201A, Ottawa, Ontario K1H 8L6, Canada.
Dr. Vendittoli: Hospital Maisonneuve-Rosemont, 5415 boul L’Assomption, Montréal, Québec H1T 2M4, Canada.
Author Contributions: Conception and design: D. Anderson, M.J. Dunbar, E.R. Bohm, E. Belzile, D. Zukor, W. Fisher, S. Pleasance, P. Wells, M. Kovacs, M.A. Rodger, P.A. Vendittoli.
Analysis and interpretation of the data: D. Anderson, M.J. Dunbar, E.R. Bohm, W. Fisher, P. Kim, N. Davis, P. Andreou, P. Wells, M. Kovacs, M. Carrier.
Drafting of the article: D. Anderson, M.J. Dunbar, E. Belzile, W. Fisher, M. Crowther, P. Kim, S. Pleasance, P. Wells, M. Kovacs, P.A. Vendittoli.
Critical revision of the article for important intellectual content: D. Anderson, E.R. Bohm, E. Belzile, S. Kahn, W. Fisher, P. Gross, S. Pelet, S. Pleasance, P. Wells, M. Kovacs, M.A. Rodger, T. Ramsay, M. Carrier, P.A. Vendittoli.
Final approval of the article: D. Anderson, M.J. Dunbar, E.R. Bohm, E. Belzile, S. Kahn, D. Zukor, W. Fisher, W. Gofton, P. Gross, S. Pelet, S. MacDonald, P. Kim, S. Pleasance, P. Andreou, P. Wells, M. Kovacs, M.A. Rodger, T. Ramsay, M. Carrier, P.A. Vendittoli.
Provision of study materials or patients: M.J. Dunbar, E.R. Bohm, E. Belzile, S. Kahn, D. Zukor, W. Fisher, W. Gofton, P. Gross, S. Pelet, M. Crowther, S. MacDonald, P. Kim, M. Kovacs.
Statistical expertise: N. Davis, P. Andreou, T. Ramsay.
Obtaining of funding: D. Anderson, E.R. Bohm, E. Belzile, S. Kahn, S. Pelet, S. Pleasance, P. Wells, M.A. Rodger, M. Carrier.
Administrative, technical, or logistic support: E.R. Bohm, S. Pelet, M. Crowther, P. Kim, S. Pleasance, N. Davis.
Collection and assembly of data: S. Kahn, D. Zukor, S. Pelet, S. MacDonald, P. Kim, N. Davis, M. Rodger, M. Carrier, P.A. Vendittoli.
The role of aspirin in thromboprophylaxis after total hip arthroplasty (THA) is controversial.
To compare extended prophylaxis with aspirin and dalteparin for prevention of symptomatic venous thromboembolism (VTE) after THA.
Multicenter randomized, controlled trial with a noninferiority design based on a minimal clinically important difference of 2.0%. Randomization was electronically generated; patients were assigned to a treatment group through a Web-based program. Patients, physicians, study coordinators, health care team members, outcome adjudicators, and data analysts were blinded to interventions. (Current Controlled Trials: ISRCTN11902170)
12 tertiary care orthopedic referral centers in Canada.
778 patients who had elective unilateral THA between 2007 and 2010.
After an initial 10 days of dalteparin prophylaxis after elective THA, patients were randomly assigned to 28 days of dalteparin (n = 400) or aspirin (n = 386).
Symptomatic VTE confirmed by objective testing (primary efficacy outcome) and bleeding.
Five of 398 patients (1.3%) randomly assigned to dalteparin and 1 of 380 (0.3%) randomly assigned to aspirin had VTE (absolute difference, 1.0 percentage point [95% CI, −0.5 to 2.5 percentage points]). Aspirin was noninferior (P < 0.001) but not superior (P = 0.22) to dalteparin. Clinically significant bleeding occurred in 5 patients (1.3%) receiving dalteparin and 2 (0.5%) receiving aspirin. The absolute between-group difference in a composite of all VTE and clinically significant bleeding events was 1.7 percentage points (CI, −0.3 to 3.8 percentage points; P = 0.091) in favor of aspirin.
The study was halted prematurely because of difficulty with patient recruitment.
Extended prophylaxis for 28 days with aspirin was noninferior to and as safe as dalteparin for the prevention of VTE after THA in patients who initially received dalteparin for 10 days. Given its low cost and greater convenience, aspirin may be considered a reasonable alternative for extended thromboprophylaxis after THA.
Canadian Institutes of Health Research.
Anderson DR, Dunbar MJ, Bohm ER, Belzile E, Kahn SR, Zukor D, et al. Aspirin Versus Low-Molecular-Weight Heparin for Extended Venous Thromboembolism Prophylaxis After Total Hip Arthroplasty: A Randomized Trial. Ann Intern Med. ;158:800–806. doi: 10.7326/0003-4819-158-11-201306040-00004
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Published: Ann Intern Med. 2013;158(11):800-806.
High Value Care, Hospital Medicine, Venous Thromboembolism.
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