Vitamin K antagonists (VKA) are the reference of anticoagulant oral therapy concerning common diseases such as Atrial Fibrillation (AF) and Venous ThromboEmbolism (VTE). In France, approximately 600,000 patients are treated with oral anticoagulants. The treatment is monitored and adjusted on the INR. Time outside the area of target INR is directly correlated with complications (thrombotic and hemorrhagic), the time in this zone mean the effectiveness of treatment. In France, monitoring patients by GP, the percentage of the time outside the target area INR higher than their European or North American comparators. To reduce complications VKA, specialized structures for monitoring anticoagulation have emerged in recent years around the world (Netherlands, Italy, UK, Canada, and USA). The evaluations in these countries show that the percentage of time in therapeutic INR range is around 70% when the patient is monitored in anticoagulation clinic (ACC), while in France this time was measured at around 50% in surveys of usual medical care. On data obtained abroad: correlation with improved monitoring INR monitoring the ACC decreases by a factor 3-4 morbidity and mortality associated with the use of VKA and thus allows a significant reduction in hospitalizations caused by adverse drug effects and thus health care costs. In France several ACC, have emerged since 1998. Ile de France since 2004, the ACC Ile-de-France called CREATIF (Centre for Reference and Education antithrombotic Ile de France). Since its inception to date, has an active list of approximately 450 patients which monitors long-term anticoagulant treatment. The question of benefit of such a structure arises, is why this has been decided to establish a prospective randomized study to evaluate the benefit of the management of oral anticoagulant treatment by CREATIF with respect to usual medical care in terms of time in therapeutic INR range. This study of usual care, witch aims to assess two types of management of anticoagulant therapy, does not alter the type of anticoagulant therapy nor its duration. The overall medical care of patient and his care pathway will also remain unchanged. The study Randomized GP investigators, is open, prospective, is concerning primary medical care (independent central randomization). Primary care investigators are GPs managing patients treated by VKAs. They were recruited in a list of GPs working with CREATIF or through several physicians networks (North Paris Health Network, ARES 92, GP Department of Paris VII university, GP Department of Paris West). CREATIF, investigators will be usual physicians working at the anti-coagulation clinic. The aim of the study is to compare the management of patients treated with VKA by the CREATIF versus their management in primary care. Therefore, the evaluation criterion is the time in therapeutic INR range. During 6 months randomized in 2 arms: GPs versus CREATIF; During the next 6 months following the reversal mode of management is to determine the existence of prolonged benefit by one followed by CREATIF after returning to his usual medical care. The investigators will also collect the retrospective 6 months INR.A retrospective study, prospective, open and multicenter with direct individual benefit. Prospective study conducted in cross-over: anticoagulant therapy for each patient will be followed by six months CREATIF then by his GP or vice VERSA.Primary analysis: comparing the two types of monitoring parallel group after randomization: Group A in Phase 1 versus Group B in Phase 1. Primary endpoint: percentage of time in therapeutic INR range.