See BCSH Guidelines on Oral Anticoagulation.
The current BCSH guideline for induction was issued in 1998 and is due for renewal. It is summarised on the Anticoagulant Chart and Referral form. In this scheme, 10mg of warfarin are given on Day 1, the day when baseline testing is performed. On Day 2 the INR must be determined again. The dosage for Day 2 may then be given, according to the algorithm. This is crucial. On Day 3 repeat the INR determination. Administer warfarin dose according to the algorithm. Again, it is crucial to dose according to the algorithm. Repeat the procedure on Day 4. From Day 5 onward, daily monitoring should be maintained until the patient is in range and stable.
It is essential that the algorithm is followed to the letter to minimise the time taken to achieve therapeutic range and to reduce the possibility of bleeding.
There is growing awareness that the above regime may not be suitable for every patient. In the elderly, in cachexic patients, in patients with liver disease, and in the Chinese population, it may be appropriate to use an alternative algorithm, based on 5mg for four days with INR determination on Day 5. Advice on this algorithm can be obtained from the Anticoagulation and Haematology Research Unit (Duty Anticoagulation Scientist bleep 582, tel 4747).
Referral to Anticoagulant Clinic
When the patient is ready for discharge, please send the Anticoagulant Chart and Referral form to the Anticoagulation Clinic having completed the form. Arrange an appointment for an anticoagulant clinic with the Clinic Supervisor, on Ext. 4798. Issue a yellow Anticoagulant Booklet completed with dosage, appointment date and time and arrange transport if necessary. Ensure that the patient has been advised on dosage and has been given adequate supplies of warfarin to last until their first clinic appointment.