The now widespread use of TTR is based upon documentation that, as the INR rises above 3.0 (and especially above 3.5 to 4.0), the risk of bleeding on an VKA increases progressively, whereas, as the TTR falls below 2.0, inefficacy with addressing the risk of thromboembolism increases progressively in patients with thromboembolic risk for which the VKA is being given. Here, TTR is linked to Thromboembolism.