Current hypothesis as of 05/12/2007:. Extending the duration of anti-thrombotic prophylaxis with aspirin by 28 days following a ten day course of Low Molecular Weight Heparin (LMWH) will be as effective at reducing the rate of symptomatic venous thromboembolic complications and will be safe and more cost-effective than extending prophylaxis by 28 days with LMWH in a group of patients undergoing total hip arthroplasty.. Previous hypothesis:. Extending the duration of anti-thrombotic prophylaxis with aspirin by 28 days following a minimum seven day course of Low Molecular Weight Heparin (LMWH) will be as effective at reducing the rate of symptomatic venous thromboembolic complications and will be safe and more cost-effective than extending prophylaxis by 28 days with LMWH in a group of patients undergoing total hip arthroplasty.. Please note that this record has been updated on the 5th December 2007 due to changes made to this protocol by the suggestion of the Research Ethics Board (REB). All changes were made prior to the recruitment of the first study participant and will be entered in this record under the date 05/12/2007.
BACKGROUND: The role of aspirin in thromboprophylaxis after total hip arthroplasty (THA) is controversial.
OBJECTIVE: To compare extended prophylaxis with aspirin and dalteparin for prevention of symptomatic venous thromboembolism (VTE) after THA.
DESIGN: 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).
SETTING: 12 tertiary care orthopedic referral centers in Canada.
PATIENTS: 778 patients who had elective unilateral THA between 2007 and 2010.
INTERVENTION: 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).
MEASUREMENTS: Symptomatic VTE confirmed by objective testing (primary efficacy outcome) and bleeding.
RESULTS: 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.
LIMITATION: The study was halted prematurely because of difficulty with patient recruitment.
CONCLUSION: 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.
PRIMARY FUNDING SOURCE: Canadian Institutes of Health Research.
Current hypothesis as of 05/12/2007:. Extending the duration of anti-thrombotic prophylaxis with aspirin by 28 days following a ten day course of Low Molecular Weight Heparin (LMWH) will be as effective at reducing the rate of symptomatic venous thromboembolic complications and will be safe and more cost-effective than extending prophylaxis by 28 days with LMWH in a group of patients undergoing total hip arthroplasty.. Previous hypothesis:. Extending the duration of anti-thrombotic prophylaxis with aspirin by 28 days following a minimum seven day course of Low Molecular Weight Heparin (LMWH) will be as effective at reducing the rate of symptomatic venous thromboembolic complications and will be safe and more cost-effective than extending prophylaxis by 28 days with LMWH in a group of patients undergoing total hip arthroplasty.. Please note that this record has been updated on the 5th December 2007 due to changes made to this protocol by the suggestion of the Research Ethics Board (REB). All changes were made prior to the recruitment of the first study participant and will be entered in this record under the date 05/12/2007.
