Oral factor Xa inhibitors for thromboprophylaxis in major orthopedic surgery: a review

The use of novel oral anticoagulants for thromboprophylaxis after elective major orthopedic surgery

Venous thromboembolism is a common cause of morbidity and mortality among patients undergoing elective orthopedic surgery. Due to the high incidence of venous thromboembolism in this setting, perioperative anticoagulation is the recommended approach for thromboprophylaxis. Low molecular weight heparin (LMWH), fondaparinux and warfarin are the agents commonly used for thromboprophylaxis. The well-recognized limitations of warfarin and the inconvenience and discomfort associated with the subcutaneous administration of low molecular weight heparin and fondaparinux inspired intense investigation to develop novel oral anticoagulants (NOACs) with more predictable pharmacokinetics, fewer drug interactions and no need for regular laboratory monitoring. Three NOACs have been demonstrated to be effective for thromboprophylaxis after total hip arthroplasty (THA) and total knee arthroplasty (TKA) in large randomized controlled trials. Here we review the pharmacology of rivaroxaban, dabigatran, and apixaban, summarize the major clinical trials of these agents in thromboprophylaxis after THA and TKA, and discuss the clinical factors to be considered by providers when selecting a NOAC for their patients.

Prevention of venous thromboembolism in acutely ill medical patients after the results of recent trials with the new oral anticoagulants

Venous thromboembolism (VTE) is a common potentially life-threatening complication in acutely ill medical patients; over 70 % of the fatal episodes of pulmonary embolism during hospitalization occur in non-surgical patients. In the absence of thromboprophylaxis, the incidence of venographically detected deep vein thrombosis is about 15 % in medical patients. Several trials and meta-analyses have clearly demonstrated the prophylactic role of unfractionated heparin, low molecular weight heparin and fondaparinux. Although over the past few years the knowledge of epidemiology, clinical features and prophylaxis in medical patients has significantly improved, there remain a number of controversial areas that require further investigation. Newer VTE risk assessment models have been proposed to select high risk hospitalized medical patients, but they still require external validation; scarce data are available to stratify patients to identify their individual bleeding risk. The optimal duration of thromboprophylaxis in medical patients is still a matter of debate; currently, extended prophylaxis after discharge is not recommended, but it may be required for subgroup of patients with persistently high VTE risk and a negligible risk of bleeding. Based on the results of recent studies, the new oral anticoagulants appear to have a very limited role, if any. However, a better risk stratification of patients who have a persistently increased risk of VTE is warranted to improve the risk to benefit profile of any anticoagulant drug to be used in this setting.

New oral anticoagulants for thromboprophylaxis after elective total hip and knee arthroplasty

Anticoagulant drugs reduce the risk of venous thromboembolic events after total hip and knee arthroplasty. However, the use of current drugs, such as low molecular weight heparins, is hampered by their subcutaneous route of administration. The use of vitamin K antagonists is hampered by the requirement for routine coagulation monitoring and dose titration to provide effective anticoagulation without an increased risk of bleeding and numerous food and drug interactions. Clearly, there is a need for new oral, fixed-dose anticoagulant drugs that do not require coagulation monitoring, while demonstrating similar or better efficacy and safety profiles when compared with current agents.