Warfarin is prescribed to a large number of people.
An international normalised ratio (INR) is used to monitor patients receiving warfarin for treatment or prevention of thrombosis and embolism. The therapeutic range of warfarin is narrow, so monitoring of INR is done to avoid complications from both over-dosage (which increases the risk of abnormal bleeding) and under-dosage (which may result in clots).
Most patients prescribed warfarin have their INR levels measured in a laboratory and receive advice from general practitioners on their next dose and testing frequency.
Now, by using this website and portable coagulometers, general practices, pharmacies and patients themselves are able to do more frequent and more convenient testing.