Optimal anticoagulant treatment lies in a small therapeutic window (an international normalised ratio (INR) close to 2.2-2.3)— irrespective of the indication for treatment. This is the conclusion of Odén and Fahlén's large study of medical records from anticoagulation clinics in Sweden (p 1073). They analysed records for 42 451 patients, with 3533 deaths and 1.25 million measurements of INR. Their results confirmed the beneficial effects of anticoagulants on thromboembolism when the INR had increased from 1.0 to 2.3 and the substantially higher mortality with higher INR. The authors conclude that more action should be taken to avoid episodes of high INR.
