Warfarin, Acenocoumarol, Phenindione

797FM.3.1 ORAL ANTICOAGULANTS – WARFARIN, ACENOCOUMAROL AND PHENINDIONE, WHEN DOSES ARE ADJUSTED BY THE ANTICOAGULATION CLINIC AND PRESCRIBED BY THE GENERAL PRACTITIONER Shared Care Protocol This protocol provides prescribing and monitoring guidance for oral anticoagulant therapy with warfarin, acenocoumarol or phenindione. It should be read in conjunction with the shared care responsibilities, the Summary of Product Characteristics (SPC) available on www.medicines.org.uk/emc and the BNF. BACKGROUND FOR USE This agreement outlines the ways in which the responsibilities for prescribing of oral anticoagulation with warfarin, acenocoumarol or phenindione are shared where the anticoagulation monitoring service recommends doses and the general practitioner (GP) prescribes them. Sharing of care assumes communication between the anticoagulant monitoring service, GP and patient. The intention to share care should be explained to the patient by both the patient’s GP and the healthcare professional initiating treatment. It is important that patients are consulted about treatment and are in agreement with it. Patients treated with oral anticoagulants are under regular follow-up, which provides an opportunity to discuss drug therapy. It is the responsibility of both the anticoagulation monitoring service and the GP to maintain competencies relevant to their roles. The anticoagulation monitoring service is responsible for ongoing audit of the quality assurance components of the service. The doctor who prescribes the medication legally assumes clinical responsibility for the drug and the consequences of its use. SUPPORTING INFORMATION The vitamin K antagonist (VKA) oral anticoagulant of choice is warfarin. A small number of patients are intolerant of warfarin and many of these are able to switch to direct oral anticoagulant (DOAC) drugs. Patients unable to tolerate warfarin who are unsuitable for DOAC drugs should have a risk assessment performed regarding the advisability of continued anticoagulation. Patients who definitely require ongoing VKA treatment should be switched to acenocoumarol. Phenindione should be very rarely, if ever required – see section on equivalent doses under switching therapy. Licensed indications Warfarin Acenocoumarol Phenindione (SINTHROME®) Prophylaxis of embolism in ✓ ✓ ✓ rheumatic heart disease Prophylaxis of stroke in atrial ✓ ✓ ✓ fibrillation Prophylaxis after insertion of ✓ ✓ ✓ prosthetic heart valves Prophylaxis and treatment of ✓ ✓ ✓ venous thrombosis and pulmonary embolism Transient ischaemic attacks ✓ Not licenced Not licensed Guideline 797FM.3.1 1 of 12 Uncontrolled if printed Patients with a therapeutic time in range less than 65%, especially if associated with frequent monitoring and erratic INR swings that are not due to poor medication adherence, should be considered for suitability for a direct oral anticoagulant (DOAC). ROLES AND RESPONSIBILITIES Where the anticoagulation monitoring service is not the patient’s GP, the responsibilities for care that are specified in this shared care protocol for oral anticoagulation apply. In this situation the anticoagulation monitoring service should request shared care using the form provided in the local shared care document. GP or hospital will refer the patient to an anticoagulation monitoring service provider. Secondary care specialist/referrer for oral anticoagulation 1. Determine the need for anticoagulation. 2. If rapid anticoagulation is required with a VKA, it is the responsibility of the specialist identifying the need for rapid oral anticoagulation to refer urgently to secondary care for initiation. 3. Where slow oral anticoagulation with a VKA is appropriate refer the patient to the anticoagulation monitoring service of their choice and inform the GP where the GP practice is not a registered ‘any qualified provider’ (AQP) site. Anticoagulant monitoring service 1. Initiate and take over management of oral anticoagulant treatment. Inform patient’s GP. 2. Provide written and verbal counselling advice on warfarin. Patients should be provided with patient information and education in an accessible and understandable format both at the initiation of oral anticoagulant treatment and reinforced at subsequent patient attendances and/or review as required. 3. If the anticoagulation monitoring service is initiating the warfarin to provide the first prescription for warfarin, titrate the dose and establish patient on a stable dose of oral anticoagulant. 4. Where a dose change warrants a change in the prescribed strengths of warfarin tablets that cannot be met with patient’s existing warfarin supply, the anticoagulation monitoring service provider must make an initial supply. 5. Provide the patient with a patient held yellow oral anticoagulant therapy record book or equivalent detailing the reason for anticoagulant therapy, target international normalised ratio (INR) range and duration of therapy and issue an oral anticoagulant alert card for them to keep on their person at all times. 6. Provide ongoing monitoring of INRs and appropriate dosing and follow up. Communicate electronically the INR results, dose prescribed and date of next INR test promptly to the patient and patient’s GP within 24 hours. 7. In cases of over anticoagulation, administer oral vitamin K in accordance with British Committee for Standards in Haematology (BCSH) guidelines and clinic protocols. 8. For all patients with an INR >5.0 the cause should be investigated. For every patient with a recorded INR of 8 or more a significant event report giving details of possible cause, management and outcome is to be completed and patient’s GP informed – AQP contract requirement. 9. Where a stop date has been clearly documented by the referrer who is not the patient’s GP then the responsibility to discontinue warfarin or other VKA resides with the anticoagulation monitoring service provider and the GP should be notified oral anticoagulation (OAC) has been stopped. 10. Where continuation of OAC is either in doubt or is not in line with national guidance this should be flagged up to the GP or referrer if this is not the patient’s GP. 11. The anticoagulation monitoring service provider must actively follow up any patient who does not attend (DNA) for regular monitoring within the agreed time period as stated in anticoagulation service specification. Guideline 797FM.3.1 2 of 12 Uncontrolled if printed 12. If a patient DNA on 2 or more consecutive occasions or there are more than 42 days in a DNA period, the anticoagulation monitoring service will contact the patient’s GP directly. 13. Report adverse events on the yellow card scheme if appropriate. 14. Ensure clear arrangements for back up advice and support are in place and patient informed. 15. Discuss and regularly review benefits and side effects of treatment with the patient. To assess treatment at regular intervals and conduct annual treatment review. To check patient is well controlled (i.e. degree of INR control should be more than 65% of time in therapeutic range in last 6 - 12 months excluding first 6 weeks of treatment) and no known contraindications to continuing treatment apply or have been identified during monitoring. The outcome of annual review is to be communicated in writing to the patient’s GP (see suggested template Appendix 1). General practitioner specific responsibilities 1. Unless initiated in secondary care before referral, the prescriber should have a documented discussion with the patient regarding the need for oral anticoagulation as well as the risks and benefits of long term treatment with warfarin. 2. Prior to referral carry out full clinical review and undertake initial full blood count (FBC), coagulation screen, urea & electrolytes (U&Es) and liver function tests (LFTs) and communicate results to the anticoagulation monitoring service. There is a standardised referral form that can be imported into the GP’s clinical system which can be used when referring to any anticoagulant monitoring service clinic to ensure capture of all essential information. Refer patient to their chosen anticoagulation monitoring provider for initiation of treatment, following a holistic assessment of the patient’s suitability for anticoagulation. The prescriber must assess the appropriateness of treatment against the patient’s current health and social status, taking into account the patient’s preferences for treatment. 3. The current chosen anticoagulation monitoring service provider should be recorded in the patient’s notes. 4. Prescribe oral anticoagulant on prescription once patient is initiated on treatment. 5. Ensure that the patient’s INR is being regularly transferred and recorded in their medical records. 6. Inform anticoagulation monitoring service if situation regarding need for anticoagulation changes following specialist advice. 7. Monitor for clinical conditions that may lead to a deterioration in health and INR stability and alert anticoagulation monitoring service in the event of any significant changes in patient’s clinical condition. 8. GP to conduct a review of the benefits versus risks of ongoing anticoagulation therapy at least annually. Details of the review should be recorded in the patient’s notes. 9. When co-prescribing, choose medicines least likely to interact with oral anticoagulant as per the interaction chart (Appendix 2). If there is a known potential interaction following any medication changes that may affect the stability of the patient’s INR, either refer the patient back to the anticoagulant clinic for

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