Medical indications and considerations for future clinical decision making

New Insights into the Pros and Cons of the Clinical Use of Vitamin K Antagonists (VKAs) Versus Direct Oral Anticoagulants (DOACs)

Vitamin K-antagonists (VKA) are the most widely used anticoagulant drugs to treat patients at risk of arterial and venous thrombosis for the past 50 years. Due to unfavorable pharmacokinetics VKA have a small therapeutic window, require frequent monitoring, and are susceptible to drug and nutritional interactions. Additionally, the effect of VKA is not limited to coagulation, but affects all vitamin K-dependent proteins. As a consequence, VKA have detrimental side effects by enhancing medial and intimal calcification. These limitations stimulated the development of alternative anticoagulant drugs, resulting in direct oral anticoagulant (DOAC) drugs, which specifically target coagulation factor Xa and thrombin. DOACs also display non-hemostatic vascular effects via protease-activated receptors (PARs). As atherosclerosis is characterized by a hypercoagulable state indicating the involvement of activated coagulation factors in the genesis of atherosclerosis, anticoagulation could have beneficial effects on atherosclerosis. Additionally, accumulating evidence demonstrates vascular benefit from high vitamin K intake. This review gives an update on oral anticoagulant treatment on the vasculature with a special focus on calcification and vitamin K interaction.

Barriers to the optimal use of anticoagulants after orthopaedic surgery

Venous thromboembolism (VTE) and the consequent morbidity and mortality associated with this condition continue to be a problem following orthopaedic surgery. The vast majority of patients undergoing orthopaedic surgery receive some form of thromboprophylaxis. However, the use of inappropriate thromboprophylaxis is an important factor which may explain why the clinical burden of VTE is still considerable. Barriers to the use of appropriate thromboprophylaxis include the belief by some surgeons that pharmacological thromboprophylaxis increases the risk of bleeding and the asymptomatic nature of deep vein thrombosis. In addition, in patients at risk of VTE, thromboprophylaxis should be given beyond the standard duration recommended in international or national guidelines, and many surgeons have concerns about adherence and adverse events in the outpatient setting. Furthermore, currently available anticoagulants have drawbacks, including the need for monitoring, or a subcutaneous route of administration. The introduction and implementation of multi-faceted and integrated approaches to thromboprophylaxis could improve adherence with current guidelines, extend appropriate thromboprophylaxis according to risk factors, and improve patient outcomes in this setting. In addition, the development of new anticoagulants with more convenient administration regimens and no need for monitoring may help to achieve these objectives.

New oral Xa and IIa inhibitors: updates on clinical trial results

Heparins and VKAs have been the cornerstones of anticoagulation therapy for several decades and these agents have become most important drugs in the primary and secondary prevention of venous and arterial thromboembolic disease. Although effective, their use has been hampered by numerous limitations. In the search for new agents matching the 'ideal' anticoagulant profile, a number of different steps in the coagulation cascade have been targeted, including direct thrombin inhibition, and direct inhibition of Factor Xa. There are currently a host of promising new agents at various stages of development and clinical evaluation. With potential benefits including predictable efficacy, rapid onset of action, ability to bind clot-bound coagulation factors and no requirement for therapeutic monitoring, these new agents are set to improve the management of thromboembolic disorders.

Economic and utilization outcomes associated with choice of treatment for venous thromboembolism in hospitalized patients

OBJECTIVES

Hospital administrative data were analyzed to assess treatment patterns, in-hospital mortality, rates of hemorrhagic events and thrombus propagation, utilization of health care resources, and hospital costs associated with various treatments during inpatient care for venous thromboembolism (VTE).

STUDY DESIGN

Data from inpatient records were collected for deep venous thrombosis (DVT) and pulmonary embolism (PE) encounters at 132 US hospitals between January 1999 and December 2000. Patients receiving the most frequently employed treatments were compared with respect to demographics, related procedures and diagnostics, length of stay, adverse events, in-hospital mortality, and hospital costs.

RESULTS

A total of 953 primary DVT and 3933 primary PE admissions were identified. Most admissions involved treatment with unfractionated heparin and vitamin K antagonist (UFH/VKA, 64.2% of admissions), followed by UFH with VKA and low-molecular-weight heparin (UFH/LMWH/VKA, 14.4%), and LMWH/VKA (12.9%). Compared with those treated with UFH/VKA, patients treated with LMWH/VKA experienced higher anticoagulant costs (dollar 540 vs. dollar 106), but lower total hospital costs (dollar 5198 vs. dollar 5977) and shorter lengths of stay (4.4 vs. 5.7 days for those without PE and 5.7 vs. 6.7 days for those with PE).

CONCLUSIONS

UFH/VKA was the most common regimen used to treat VTE. In spite of its higher medication cost, however, treatment with LMWH/VKA was associated with significantly shorter hospital stays and lower total hospitalization costs, compared with UFH/VKA.

[An update on thrombosis prophylaxis in orthopaedic and accident surgery]

The prevention of deep venous thrombosis has become a routine in orthopaedic surgery. While the necessity for prophylaxis is not questioned, its practice is still a matter of controversy. The development of new anticoagulants increases the variety of prophylactic methods but leads to a need for additional information. This review deals with the indications for thrombosis prophylaxis in relation to exposing and predisposing risk factors. The currently available modalities of prophylaxis, their pharmacological details and clinical significance are presented. Evidence based data, recommendations on the duration of prophylaxis derived from official guidelines, issues of the cost/effectiveness, and medico-judicial aspects are discussed.