Use of warfarin for venous thromboembolism prophylaxis following knee and hip arthroplasty: results of the Michigan Anticoagulation Quality Improvement Initiative (MAQI2).

Total knee arthroplasty (TKA) and total hip arthroplasty (THA) are associated with high rates of venous thromboembolism (VTE). Anticoagulants, such as warfarin, are commonly used to prevent VTE in such patients. The practice and effectiveness of warfarin in real world populations is not well documented. 595 TKA and THA patients treated with warfarin were followed by two anticoagulation clinics in the Michigan Anticoagulation Quality Improvement Initiative. Length of prescribed anticoagulation, percent time in therapeutic range (%TTR) and time to first therapeutic INR were calculated for each surgical group. For THA, all 300 patients received at least ten days with a 28-day median length of anticoagulation therapy. For TKA, all 295 patients received at least 10 days with a 28-day median length of anticoagulation therapy. For THA patients, time to first therapeutic INR was on average 12.0 ± 8.0 days with a mean %TTR of 36.6 ± 26.8% for goal INR 2.0-3.0. For THA patients, 39 (13%) never reached target INR. For TKA patients, time to first therapeutic INR was on average 12.8 ± 10.3 days with a mean %TTR of 36.0 ± 28.3% for goal INR 2.0-3.0. For TKA patients, 44 (14.9%) never reached target INR. Many orthopaedic surgeons who use warfarin for post-arthroplasty VTE prophylaxis do so in accordance with national guidelines. The time to first therapeutic INR is strikingly long and %TTR markedly low for these patients, raising questions about the efficacy of warfarin therapy in the first 1-2 post-operative weeks. Further studies to investigate the best target INR for warfarin prophylaxis, as well as the composite rates of VTE and clinically relevant bleeding from treatment with warfarin, LMWH and newer anticoagulants are needed.

Changing practice: implementation of a venous thromboembolism prophylaxis protocol at an academic medical center.

BACKGROUND: The Institute of Medicine has identified a "quality chasm" between existing evidence and actual clinical practice. The Venous Thromboembolism Prevention Study has shown that enoxaparin prophylaxis is a safe and effective way of preventing postoperative venous thromboembolism. This article presents a "how-to" guide for implementation of a venous thromboembolism prophylaxis protocol. METHODS: The Venous Thromboembolism Prevention Study prophylaxis protocol included provision of postoperative, prophylactic dose enoxaparin for the duration of inpatient stay. Compliance was considered at the individual patient level and defined as appropriate provision of protocol-appropriate enoxaparin prophylaxis. Multiple simultaneous interventions to improve protocol compliance were undertaken. Both physician and physician assistant "champions" were identified. Interventions included staff and surgeon educational sessions, discussion of venous thromboembolism-themed articles at journal club, and monthly e-mail reminders specific to the protocol, among others. Compliance rates over time were compared using the chi-square test. RESULTS: The authors reviewed medical records from 945 consecutive admissions to the plastic surgery service who met Venous Thromboembolism Prevention Study eligibility criteria over a 30-month period. Initial education sessions significantly increased compliance over baseline (55 percent versus 10 percent; p<0.001). After formal protocol adoption, compliance increased steadily over the first 9 months and peaked by 1 year. In the absence of any direct intervention, compliance remained stable at 90 percent for the final 12 months of the study. This was significantly increased when compared with the period of time immediately following protocol adoption (90 percent versus 77 percent; p<0.001). CONCLUSION: This article provides readers with a practical approach for implementation of a venous thromboembolism prophylaxis protocol at their hospital.