Warfarin Guidelines

Howden Warfarin Protocol

Initiation of Warfarin in Primary Care (West Lothian)

Howden Warfarin Protocol

Patient Group

Patients on oral anticoagulants (Warfarin)
New patients after referral from hospital or GP

Individual Responsibilities

Patients

• Carrying anticoagulant record book which states:
      Target INR
      Contact numbers
      Referring doctors
      Doctor managing treatment
• Attend for blood tests, as instructed.
• Alter dose as instructed.
• Keep a personal record of dose and INR in book.

Practice Nurses

• Perform blood tests
• Ensure that each patient has an anticoagulant book
• Ensure patients are aware of the risks of Warfarin in relation to alcohol consumption etc.
• Teach identification of side effects etc

GP

• Workflow for INR results
• Result received from laboratory via electronic link (GP initiates link).
• GP records INR, dose and review interval on GPASS SPICE Warfarin screen.
• GP completes letter template with result & dosing instructions for patient.
• GP only contacts patient by telephone if dose change needed, or if retesting required within 2 weeks.
• Letter posted with instructions to all patients.

Office staff

Fortnightly search is performed on computer to identify patients who are late for repeat INR checks, and they are contacted by phone or letter.

GUIDELINE FOR THE INITIATION OF WARFARIN IN PRIMARY CARE

West Lothian Healthcare NHS Trust

General Practitioners are being asked with increasing frequency to initiate warfarin in the community, often in older patients with atrial fibrillation where there is no need for rapid warfarinisation. This guideline for the gradual introduction of warfarin has been modified from one developed and tested in secondary care in patients similar to those seen in general practice.

This guideline is only for initiating warfarin in non-acute situations
e.g. in patients with pre-existing atrial fibrillation.

Before commencing treatment, it is important to consider whether the patient might be especially sensitive to warfarin (see BNF).

· Is the patient on drugs, which interact with warfarin e.g. analgesics, amiodarone, some antibacterials, St John’s Wort, antiepilectics, antifungals, lipid regulating drugs, some ulcer healing drugs? (See BNF for more extensive information).

· Do they have a pre-existing abnormal liver function or INR, heart failure, low weight or age >80?

· Is the patient's alcohol intake of concern?

· If concerned about sensitivity, consider more frequent monitoring or start at lower dose/seek specialist advlce*.

The guideline is intended to give an INR of 2.0-3.0 at 6 weeks. People with different target ranges could still start this way and further adjustments made after 6 weeks. INRs only have to be done at weekly intervals and the dose of Warfarin only changes if the INR is >3.0 or persistently <1.5. Note that the INR at 14 days predicts the maintenance dose. In weeks 3-6, adjust dose according to the INR, which is routinely checked once a week.

ADJUST DOSE DURING THIS PHASE AS FOLLOWS:

IN THIS CASE THE GUIDELINE BECOMES INVALID. FURTHER ADVICE IS AVAILABLE FROM CONSULTANT HAEMATOLOGIST, ST JOHN'S HOSPITAL.

PREDICTED MAINTENANCE DOSE TABLES

TABLE 1 -MALES