Anticoagulation UK

Anticoagulants and monitoring

There are currently five main oral anticoagulants.

Apixaban (Eliquis), Dabigatran (Pradaxa), Edoxaban (Lixiana), Rivaroxaban (Xarelto) and Warfarin.

Apixaban, Dabigatran. Edoxaban and Rivaroxaban are known as Direct Oral Anticoagulants (DOACS) sometimes also called Novel Oral Anticoagulants (NOACS).

Warfarin is known as a Vitamin K Antagonist (VKA).

Monitoring DOACS

The DOACS do not need monitoring in the same way as warfarin and there is no requirement for regular blood tests to see what levels of the drug are in your body.

This does not mean that there are no checks to be made. You should have a blood test before you start taking them. This is to check your kidney function (renal function) and liver function. You will need to have this blood test at least once a year. This will vary from person to person and your doctor will tell you when you need to have this.

When these anticoagulants received their licence it was widely reported that they “needed no monitoring”. Subsequently The National Institute for Health and Care Excellence (NICE) has produced a Clinical Knowledge Summary (CKS). This gives further guidance around how these anticoagulants should be monitored.

The CKS says:

How should I monitor someone taking Apixaban, Dabigatran, Edoxaban or Rivaroxaban (DOACS) ?

Although there is no need for regular blood tests to monitor the international normalized ratio (INR) as for warfarin, people taking DOACS require regular follow up and monitoring.

  • Baseline clotting screen, renal and liver function tests, and a full blood count should be performed at the start of treatment.
  • Ideally the person should be assessed every 3 months in order to:
    • Assess compliance with treatment and reinforce advice regarding the importance of a regular dosing schedule.
    • Enquire about the presence of any adverse effects such as bleeding.
    • Assess for the presence of thromboembolic events (e.g. symptoms of stroke, or breathlessness - may suggest a pulmonary embolism).
    • Ask the person if they have been taking any other medicines including any bought over-the-counter.

Monitoring warfarin

Warfarin is taken as a once a day medicine and doses are dependent on the persons needs to balance clot prevention and bleeding risk. Warfarin can sometimes be referred to as a ‘blood thinner’ however, it doesn’t actually make the blood thinner. It works by interfering with the process of how clots are formed so that the blood takes longer to clot.

When starting warfarin treatment, it is very important that people are given information about the need for regular blood tests to check their International Normalised Ration (INR) level. Some people stabilise on warfarin very quickly, whilst others may take longer and need frequent dose adjustments.

Warfarin levels can be affected by diet, alcohol and other medications, over the counter drugs and herbal and homeopathic remedies. Your healthcare professional should provide you with information about how to manage your treatment.

Blood tests

You will need to have regular blood tests to check your INR (international normalised ratio) and these may be carried out at the hospital, your GP practice, at a pharmacy or other community setting. The blood tests may be a venous sample (blood taken from a vein in your arm) or a finger prick test using a hand held device known as a coagulometer.

The coagulometer will give an instant INR result and will be stored in the memory of the device. Depending on the condition that you are being treated for, each person will have a therapeutic range which they need to be in to give maximum protection against clots and to reduce any risk of unnecessary bleeding. If you have your blood tested in this way, your nurse, doctor or pharmacist will then advise you of any dose adjustments necessary and make an appointment for your next blood test.

Self–monitoring of your INR

People who are on long-term warfarin treatment may wish to be trained to self–monitor their INR at home by using a hand held device for this purpose. Self-monitoring encourages self-care and can promote a positive approach to managing long-term condition and is a key NHS initiative. Self–monitoring is a convenient way to check your INR at anytime and avoids the need to attend clinics and waiting time for the results.

For those working, this is a real incentive as it reduces the time away from the work environment and with a growing older workforce can be invaluable in helping individuals manage their healthcare in a positive way.

For younger people at school or university, taking time out of school to attend for blood tests can be disruptive and a constant reminder that they have a long-term condition. The impact on family carers in getting young and older people to clinics can be significantly reduced if self–monitoring is introduced.

Getting started

It is advisable to talk to your doctor, or the person managing your warfarin treatment, to discuss your options around self–monitoring. At the present time, the monitors are not available on prescription from the NHS but the strips used in the monitors to measure the INR readings are available on prescription.

Before purchasing a coagulometer, you should discuss this option with your doctor as whilst some GPs are very keen to encourage patients to self–monitor, the decision to support patients may not be endorsed by the local clinical commissioning group who direct prescribers as to what can and can’t be offered to patients.

To use the device effectively, people will need to be able to use a lancet pen to obtain a drop of blood to place on the strip and this requires and have reasonable eyesight to see where the blood needs to be placed and read the INR result which appears on the screen in bold letters. Carers and parents can of course help with someone who cannot manage this.

You will be shown how to use the monitor and the doctor or nurse will want to be sure that you can use the monitor effectively in order that the INR results can be recorded. You would then be asked to send your results to the doctor or nurse. There are many ways you may be asked to do this such as by text, by telephone or email. You will then be contacted with the result of your test and if necessary any dose adjustments that need to be made.

Some long-term users may want to progress to self–management. Self-management is where you test the blood and make the dose adjustments yourself. Your doctor or nurse would teach you how to do this and you can also access guidance using online resources.

The monitors were approved by the National Institute for Health and Care Excellence (NICE) in 2014 and the recommendation is that for people who have atrial fibrillation and for people who have replacement heart valves, self–monitoring should be considered:

  • if preferred by a patient if the patient (or carer) is physically and cognitively able to perform the test
  • an adequate supportive educational programme is in place to train patients/carers
  • the patient’s ability to self-manage
  • the device is regularly checked via a quality control programme

Recent developments have seen the introduction of self–monitoring being offered to a broad population across a specific region.  This forms part of the anticoagulation services on offer and provides a complete package for the patient who can use a dedicated telehealth system to update their INR results to a central point which is managed by experienced anticoagulation nurses.

For people outside of these schemes, you may need to consider purchasing your own monitor, as they are not available on prescription. The testing strips used in the monitors have been available on prescription since 2002. ACUK are aware that some GPs are unwilling to prescribe them. Both the monitors and the testing strips can be purchased direct from the manufacturer.

There are many aids and Apps to help you look after yourself whilst taking anticoagulants. They give you advice, let you record your INR and other important information, remind you when to take your medication.

One such example is the Engage App. See below.

You can also watch a video of someone who is successfully self-monitoring their INR, see an infographic on self-monitoring and download our “Busting the myths of self-monitoring” document.

Watch Roys story of self testing his INR