Extended Venous Thromboembolism Prophylaxis Comparing Rivaroxaban to Aspirin Following Total Hip and Knee Arthroplasty

Inclusion criteria

• All patients undergoing elective total hip or knee arthroplasty at the participating institutions will be potentially eligible for this study

Exclusion criteria

• Hip or lower limb fracture in the previous three months
• Metastatic cancer
• Life expectancy less than 6 months
• History of major bleeding that in the judgment of the investigator precludes use of anticoagulant prophylaxis
• History of aspirin allergy, active peptic ulcer disease or gastritis that in judgment of investigator precludes use of aspirin
• History of significant hepatic disease or any other condition that in the judgement of the investigator precludes the use of rivaroxaban
• Creatinine clearance less than 30 ml per minute
• Platelet count less than 100 x 109 /L
• Need for long-term anticoagulation due to a preexisting co-morbid condition or due to the development of venous thromboembolism following surgery but prior to randomization
• Did not or will not receive rivaroxaban post-operatively for VTE prophylaxis
• Bilateral total hip arthroplasty or simultaneous hip and knee arthroplasty
• Major surgical procedure within the previous three months
• Requirement for major surgery post arthroplasty within 90 day period
• Chronic daily aspirin use with dose greater than 100 mg a day
• Women of child bearing potential who are not abstinent or do not use appropriate contraception throughout the study drug period
• Geographical inaccessibility for follow-up
• Unwilling or unable to give consent
• Previous participation in the study
• Concomitant use with drugs that are strong inhibitors or inducers of both P-gp and CYP3A4