Each approach has its advantages and disadvantages. which the TTR was measured since the confirmation of the analysis of VTE. Results Forty studies were included (26064 individuals). The weighted means of TTR were 54.0% in the first month since the start of treatment, 55.6% in months 1 to 3, 60.0% in months 2 to 3 3, 60.0% in the months1 to 6+ and 75.2% in months 4 to 12+. Five studies reported TTR in classes. The INR in these studies was 67% of time in restorative range in 72.0% of the patients. Summary Reported quality of VKA treatment is definitely highly dependent on the time-period since the start of treatment, with TTR ranging from approximately 56% in studies including the 1st month to 75% in studies excluding the 1st 3 months. Intro Traditionally, individuals with venous thromboembolism (VTE) are treated with low molecular excess weight heparins (LMWH) and vitamin K antagonists (VKA) such as warfarin, acenocoumarol or phenprocoumon [1], [2]. As with any medical treatment, the weighing of risks and benefits must be cautiously balanced. The effect of VKA therapy depends on many factors including variance in dose response between individuals, individual variance in pharmacokinetics and pharmacodynamic response, multiple relationships with food, co- medication and finally also by variance in adherence [3], [4]. VKA have a narrow restorative index, which needs to be monitored cautiously in order to reduce the risk of tromboembolic events as well as bleeding complications [5]. With the large scale medical testing of novel, direct acting oral anticoagulants, including the thrombin and element Xa inhibitors dabigatran and rivaroxaban, a new era has been heralded. The main advantage of these fresh anticoagulants is the lack of a need for laboratory monitoring and dose adjustment mTOR inhibitor (mTOR-IN-1) due to more stable pharmacokinetics [6]. Several recent large randomized controlled tests have shown non-inferiority in performance and security mTOR inhibitor (mTOR-IN-1) of the new anticoagulants compared to VKA treatment [7], [8], [9], [10], [11]. However, the percentage of time within restorative range in the VKA-group, representing the quality of the control group, appears to vary substantially among these studies. The International Normalized Percentage (INR), the percentage of a patient’s prothrombin time to a normal (control) sample, raised to the power of the International Level of sensitivity Index (ISI) value, is established from the World Health Corporation (WHO) and the International Committee on Thrombosis and Hemostasis for monitoring the effects of VKA. A target INR range of 2.0 to 3.0 is recommended for the treatment of VTE [3]. The most recognized way to measure the restorative performance of VKA over time is to measure the percentage of time in the restorative mTOR inhibitor (mTOR-IN-1) range (TTR). TTR offers been shown to strongly correlate with the medical results of hemorrhage or thrombosis and, thus, TTR is definitely a reliable measure of the quality of anticoagulation management [12]. Dabigatran and rivaroxaban have been recently authorized in many countries including the USA, Canada and also in Europe. This development will cause major changes in thrombosis management in the near future. Cost-effectiveness studies and real life registries will be CANPL2 the next step in the implementation of fresh oral anticoagulants. In order to properly compare all treatment options, including novel anticoagulants and VKA, and to interpret the relative effectiveness and security of these novel anticoagulants, it is important to properly assess the quality of anticoagulant control, i.e. TTR, in the VKA group. This systematic review tries to provide a benchmark of TTR in individuals with VTE receiving VKA and discusses the pros and cons of various ways to determine TTR. Finally, it emphasizes the need to standardize TTR reporting, therefore contributing to a meaningful.