We describe the risk of symptomatic venous thromboembolism and clinically relevant bleeding in a retrospective cohort of patients receiving low-intensity warfarin (INR 1.5 to 2.5) for six weeks after total hip arthroplasty. Outcomes were identified within a joint replacement registry and cross-verified by queries of electronic inpatient and outpatient databases and independently adjudicated by chart review.
835 surgeries in 800 patients were included in the analysis. Mean patient age was 66 years, 61.7 % were female and 81.1 % were prescribed mechanical prophylaxis in addition to warfarin. In the 90 days after surgery, there were 13 cases of symptomatic venous thromboembolism (1.6 % of surgeries) which included 10 cases of pulmonary embolism (1.2 % of surgeries). The incidence of clinically relevant bleeding during warfarin therapy was 0.8 % and one death unrelated to bleeding or venous thromboembolism occurred.
Although warfarin produced low rates of clinically relevant bleeding and symptomatic venous thromboembolism, pulmonary embolism made up a greater proportion of events than anticipated. Low-intensity warfarin should be considered in future studies to identify the regimen that optimally balances risk of bleeding and symptomatic venous thromboembolism in a real world setting.