A Safe, Effective, and Easy to Use Warfarin Initiation Dosing Nomogram for Post–Joint Arthroplasty Patients

Abstract Venous thromboembolism (VTE) is a complication after joint arthroplasty, and pharmacologic prophylaxis is recommended to reduce this risk. Warfarin is often used, but initial dosing and management can be difficult. We studied a single-center prospective cohort of consecutive (n = 351) post–joint arthroplasty/revision patients who were initiated on warfarin using a new initiation nomogram and then discharged to home with home health services. The mean time to an international normalized ratio (INR) of 2.0 or higher was 5 days, with a mean INR of 2.1 on the fifth postoperative day. Two patients (0.6%) had an INR higher than 5 in the first 10 days of therapy. Adverse events were uncommon: 4 patients (1.14%) had VTE, 1 had major bleeding episode, and 6 patients (1.7%) had minor bleeding. A specific warfarin dosing nomogram managed by an anticoagulation service and used in joint arthroplasty/revision patients who are discharged to home with home health services leads to effective anticoagulation with few associated adverse events.