 This multi-center study is designed to evaluate the ability of intended lay users patients on oral anticoagulation therapy, OAT, or their caregivers to 1 operate the INRatio Prothrombin Time PT Monitoring System utilizing the INRatio test strip newly designed for low sample volume and heparin insensitivity, and 2 obtain accurate results for the quantitative determination of International Normalized Ratio INR when self-testing using fingerstick capillary blood. Patients will be trained by their healthcare provider using the instructions for use and product labeling provided. The accuracy of the patient INR results will be assessed by comparison to the INR results obtained by the sites trained healthcare professional using the same INRatio system from a separate fingerstick collected from the same patient at the point-of-care, and with the INR results obtained on venous plasma obtained from the same patient and analyzed at a central laboratory with the Sysmex CA-560 System INR reference method. 