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Stop the clot: INR monitoring in practice

4 October 2010

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BA(Hons) MSc DMS

Psychologist and Management Consultant

Strategic Management Partner (part-time)
Tamar Valley Health, Cornwall

Kathie juggles her own primary care consultancy with a part-time partnership in a large, rural practice. After nearly 30 years spent working nationwide with practices and PCTs, she can testify to the fact that each year in general practice is busier than the last. When not working, Kathie rides her horse on Bodmin Moor and tries to forget about work

Warfarin is widely used in the management of conditions such as deep vein thrombosis (DVT), pulmonary embolisms (blood clots in the lungs), atrial fibrillation (irregular heartbeat) and following myocardial infarctions (heart attacks).

Although effective in the treatment of such conditions, it can have potentially fatal side effects. This is because it works by thinning the blood (by slowing the production of Vitamin K, which is needed for blood clotting) to enable an uninterrupted blood flow. If the blood thins too much, haemorrhage can result.

The International Normalised Ratio (INR) level measures the warfarin-induced delay in blood clotting. Although 1 is “normal”, other health factors have to be taken into account when assessing a patient’s INR, and levels of between 2.0 and 4.5 are usually targeted, depending on the precipitating health problem.

The aim of anticoagulation monitoring is to keep the patient’s levels within an agreed range for their particular condition and state of health. This is done by varying the dose of warfarin to counterbalance any discrepancies between their test results and target levels.

Warfarin therapy is generally for specified periods of time, such as 6-12 months. However, some patients may require lifelong treatment. Patients initially require frequent tests until a suitable dosage is achieved. Thereafter, they will require regular monitoring until the medication is discontinued: this might be at intervals of up to 10 weeks for well-controlled patients.

Because of the need for regular, and sometimes frequent, blood tests, anticoagulation monitoring is usually most convenient for patients when carried out in primary care. Such a service may also have the advantage of being more personalised, owing to the patient’s familiarity with their local practice. While not every practice is able to offer inhouse testing, the ability for patients at least to have their doses controlled by the practice is likely to be popular with patients on warfarin.

INR national enhanced service
As part of the 2004 GP contract, enhanced services were introduced that enabled practices to take on certain optional services, where commissioned by their primary care organisations (PCOs), including running INR clinics. The specification for this service includes the following requirements:

  • A register of INR patients, including the indication (or reason) for treatment, its proposed length and the target INR, and a recall system for such patients.
  • Joint working with other healthcare professionals, and appropriate training for 
all those involved.
  • Education of patients and their carers on potential side-effects, and the provision of individual management plans (including the planned duration and target INR).
  • Patient reviews (upon diagnosis and at least annually thereafter), including checks for potential complications. Records must be kept of any episodes of haemorrhage requiring hospital admission, and any admissions or deaths due to warfarin must be reported to the relevant primary care organisation (PCO) within 72 hours.
  • Clinical audits and annual reviews must be undertaken, including details of any incidents of haemorrhage or deaths, and the success of the practice in maintaining patients within the designated INR range should be assessed. The review includes details of any computer-assisted decision-making equipment used and how internal and external quality assurance is maintained.

The national enhanced service (NES) offers various levels, ranging from testing and dosage carried out by the hospital to the practice doing it all inhouse. The NES has given way to local variations nationwide since it was introduced, and practices will need to obtain copies of the local guidelines and fees from their PCOs.

The initial fees for level 3, for example (practice-funded phlebotomy, laboratory test and practice dosing) were £80-110 per patient per year, while those for level 4 (with requirements as for level 3 but with testing done inhouse by the practice) were £85-120. Domiciliary visits to housebound patients should attract an 
additional fee.

The practice manager’s role
The anticoagulation monitoring for individual patients requires close clinical supervision but the practice manager has a significant role to play in the overall delivery of the system. This is often especially relevant for meeting the requirements of the enhanced service specification (national or local) and for the collection and review of aggregated data about the service.

If the practice has a lower-level enhanced service, the manager could also consider seeking internal interest and PCO agreement to raise the level so that the practice has greater autonomy.  For example, if the practice uses an externally provided phlebotomy service, an INR clinic might provide the opportunity to bring this service inhouse.

If the practice relies on external testing, a further increase in level can be obtained by setting up an inhouse service. This can be done by the use of a coagulometer system such as CoaguChek. The advantages of such a system are that the patient no longer has to have a full blood sample taken but instead has a finger-prick test by a healthcare assistant (HCA) or nurse.

Since the results are available without having to wait for a full blood specimen to be sent to the local lab, analysed and then phoned through, the patient can be advised of their results immediately. At the same time they can be informed of any actual or potential dosage changes.

Practices with an INR service also have the option of using decision-support software, such as INRstar, to assist with calculating correct dosages when these need to be changed.
The results obtained from either the local lab or inhouse testing are entered into the system, which then advises of the appropriate dose. This notification can then be printed out and given to the patient, and a copy provided for their GP to check.

What problems can arise?
The manager should ensure the following:

  • The practice needs a clinical lead who will oversee the service, deal with any clinical problems and undertake the clinical element of the audit.
  • The enhanced service requirements must be fully understand and, where possible, achieved at the highest level on offer locally.
  • A robust system of obtaining patients’ blood results (either from the lab or the inhouse equipment), establishing dosage requirements, dealing with any fluctuations or problems, and then notifying patients of their results and doses must be in place at all times, with risk-resistant procedures and clear written protocols.
  • Comprehensive patient records must be 
kept, with those from supplementary systems, such as CoaguChek and INRstar, entered into the GP computer system to provide a central record.
  • Relevant health and safety policies, such as those relating to the use of reagent test strips and blood tests, must be in place.
  • The profitability of the system should be monitored, and procedures set up for accurate and timely claiming.
  • Governance issues must be followed as directed: for example, inhouse testing has to go through periodic internal and external quality control to ensure its accuracy. 
  • Robust procedures must be set up to ensure warfarin patients are recalled and followed up if they fail to attend, that they are able to get prescriptions as needed, and that supplies such as reagent strips and computer updates are obtained in a timely manner.

Setting up an INR clinic is a complex and time-consuming process but, once established, it should run smoothly. Although the practice needs to invest time, money and clinical expertise in its INR service, the results are usually positive for patients, rewarding for the staff involved and profitable for the practice.


National Centre for Anticoagulation Training

National Patient Safety Agency