British Society for Haematology recommended therapeutic intervals.
Prophylaxis of deep venous thrombosis (DVT), including high risk surgery: 2.0-2.5. Prophylaxis of DVT for hip surgery, surgery for femoral fracture; treatment of DVT, pulmonary embolism, transient ischaemic attacks: 2.0-3.0. Recurrent DVT and pulmonary embolism; arterial disease including myocardial infarction, arterial grafts, cardiac prosthetic valves and grafts: 3.0-4.5.
The European literature recommends an INR of 2.5-4.8, with a level of 3.6-4.8 for mechanical valves.