The NICE diagnostics guidance on self-monitoring coagulometers supports the use of the Coaguchek XS system (Roche Diagnostics) and the InRatio2 PT/INR Monitor (Alere) as options for some adults with atrial fibrillation or heart valve disease who are on long-term anticoagulation therapy such as warfarin, and who are at higher risk of developing blood clots, to self-monitor the time it takes for their blood to clot (coagulation).
The devices monitor how quickly blood clots using a measure known as the international normalised ratio (INR). The INR enables the dose of anticoagulant to be adjusted if required. This in turn can help prevent major bleeding, heart attack or stroke that can result from an over- or under-dose of anticoagulant.
Self-monitoring can involve either self-testing (where the user performs the INR test themselves and then contacts their health professional for advice on any change to the dosage of anticoagulant that may be required) or self-managing (where the user performs the INR test themselves and then adjusts the dosage of their anticoagulant medication by following an agreed care protocol).
“The evidence shows that greater use of self-monitoring offers clinical and patient benefit and, over time, is likely to result in reductions in heart attacks and strokes caused by blood clots,” says Professor Carole Longson, NICE Health Technology Evaluation Centre Director.
“People on long-term anticoagulation need to monitor their blood regularly to make sure they are taking the right dose of their drug. Apart from the anxiety associated with waiting for the results from an anticoagulation test and in continuing normal daily activities without knowing the risk of a bleed or clot, the time and cost of attending an anticoagulation clinic can be a significant burden for people on long-term oral anticoagulation therapy and can significantly affect both their working and family life.
“Because self-monitoring provides almost instant results, self-monitoring can reduce anxiety, provide a sense of control for the patient and remove the need to frequently attend clinics or hospitals. The Committee also heard that self-monitoring allows people to visit, or act as a carer for, other family members, without having to worry about attending testing appointments.”
The diagnostics guidance for self-monitoring coagulometers is available on the NICE website.
Notes to Editors
NICE Health Technologies Adoption Programme
- The NICE Health Technologies Adoption Programme is currently working with a number of NHS organisations to produce an adoption support resource for self-monitoring coagulation status in people on long-term vitamin K antagonist therapy who have atrial fibrillation or heart valve disease: point-of-care coagulometers. This will contain practical solutions and advice to support other organisations that may want to start using these technologies in the future.
About atrial fibrillation
- Currently, around 835,000 people in England have AF and estimates suggest this number is increasing.
- AF occurs when the electrical impulses controlling the heart rhythm become disorganised, so that the heart beats irregularly and, occasionally, too fast and so cannot pump blood around the body efficiently. This may cause symptoms such as palpitations, chest pain or discomfort, shortness of breath, dizziness and fainting. Severe symptoms can be life-threatening and require immediate treatment. However, many people with AF – perhaps as many as a third - don’t have any symptoms.
- AF leads to deterioration in the mechanical function of the atria (the upper chambers of the heart which receive blood returning to it from other areas of the body) and prevents complete expulsion of blood from the heart. People with AF have a higher risk of having a stroke because the blood can become stagnant and form blood clots.
- Approximately 47% of people with atrial fibrillation currently receive vitamin K antagonist therapy. It is estimated that a further 30% of people with atrial fibrillation could receive this therapy but currently do not.
- People with atrial fibrillation are at a 5-6 times greater risk of stroke, with 12,500 strokes directly attributable to atrial fibrillation every year in the UK. Treatment with warfarin reduces this risk by 50–70%.
About heart valve disease
- Valve disease can affect blood flow through the heart in two ways; valve stenosis, where the valve does not open fully, and valve regurgitation (or incompetence) where the valve does not close properly, allowing blood to leak backwards. Disease can occur in any of the four heart valves, although disorders of the aortic and mitral valves are more serious.
- The main causes of heart valve disease are congenital heart disease and other diseases such as rheumatic fever, lupus, cardiomyopathy or endocarditis. Aortic stenosis is the most common type of valve disease and it affects around one in 20 adults over the age of 65 years in the UK.
- Data from the UK heart valve registry indicate that approximately 0.2% of the UK population has prosthetic heart valves. Around 6500 adult heart valve replacements (using mechanical or biological valves) are carried out each year, of which around 5000 are aortic valve replacements.
- Patients with mechanical heart valves (and some patients with bioprosthetic valves) are susceptible to thromboembolism and need lifelong anticoagulant therapy.
About Coaguchek XS system
- The Coaguchek XS system (Roche Diagnostics) comprises a meter and specifically designed test strips which can analyse a blood sample (fresh capillary blood or fresh untreated whole venous blood) and calculate the prothrombin time (PT) and the international normalised ratio (INR). These measures indicate the rate at which the blood clots. If the INR is too low, there is a higher risk of blood clots which can lead to a heart attack or a stroke. If the INR is too high, there is a higher risk of bleeding which in severe cases can be gastrointestinal or intracerebral bleeding.
- A code chip, which contains calibration data and the expiry date of the test strips, is inserted into the meter before it is switched on. Once the device is switched on, a test strip is inserted and the blood sample is applied. The test result is displayed approximately 1 minute after application of the sample and the monitor automatically stores the result in memory. The user is guided through the process by on-screen graphical instructions.
About InRatio2 PT/INR Monitor
- The INRatio2 PT/INR monitor (Alere) does a modified version of the 1-stage prothrombin time test using a recombinant human thromboplastin reagent. The clot formed in the reaction is detected by the change in the electrical impedance of the sample during the coagulation process. The system consists of a monitor and disposable test strips.
- The monitor provides a user interface, heats the test strip to the appropriate reaction temperature, measures the impedance of blood samples, and calculates and reports prothrombin time and INR results. Instructions and test results are displayed on an LCD. The monitor can store the results so that past test results can be reviewed.
About the NICE Diagnostics Assessment Programme
- For further information about the NICE diagnostics assessment programme see Developing NICE diagnostic technologies guidance
- Topics to be considered by the Programme are routed through the related Medical Technologies Evaluation Programme. Further information about this can be found at Developing NICE medical technologies guidance
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