The challenge

The INR Self-Testing Service was developed by Health Call in partnership with County Durham and Darlington NHS Foundation Trust.

Patients who have their INR levels monitored typically need to regularly present at hospital or their care provider. Patients who are prescribed warfarin need to have their international normalised ratio (INR) measured regularly. INR tells you long it takes your blood to clot. The longer it takes your blood to clot, the higher your INR.

The INR result is used to determine the dose of warfarin patients need to take. Patients who take warfarin typically need to regularly present at hospital or their care provider to have their INR taken.


Leaflet – INR Self-Testing Service

Case study – INR Self-Testing Service

Patient leaflet – INR Self Testing Service

Video – NHS X INR

how does it work

Patients on the self-testing pathway are trained so they can administer their own test and securely share their results back to their healthcare team.

The patient receives a text message reminder for them to submit their readings.

Their device provides the reading for the patient to submit to their clinical team. Their nursing team reviews the reading and provides a message back, through the patient’s preferred method of communication about their dosage.

Healthcare practitioners can contact the patient directly to speak to them about any irregular readings or adverse responses.

The benefits of INR self-testing

Following the implementation at County Durham and Darlington NHS Foundation Trust, an evaluation took place which found:

  • Over 70 per cent of patients improved their time in therapeutic range by 20 per cent and a 24-month follow up showed that this change is long lasting.
  • 100 per cent patients using the service said they’d recommend it to others.
  • INR self-testing was 17 per cent cheaper than face-to-face clinic appointments and 25 per cent cheaper than home visits.
  • An estimated 20-25 per cent of patients on warfarin would benefit from INR self-testing, which could reduce out-patient appointments by over 20 per cent.

patient information: INR self-testing service

What is the INR Self-Testing Service?

The INR Self-Testing Service is designed to help patients manage their INR from home, reducing the need to travel to the warfarin clinic. Using our digital health technology, a patient can take their blood test at home and submit the readings weekly. If any readings are irregular, a clinician will get in contact immediately.

What is involved in the Health Call INR Self-Testing Service?

You will receive full training on how to test your blood using the digital health self-monitoring devices. You will arrange with your clinician for an automated phone call or email on the same day and time each week. The phone call or email will ask you a few questions around your general health and well-being and will ask you to submit your reading.

Your readings will be checked by the warfarin clinic nurse who will then decide your next dosage which will be communicated to you by another automated phone call or email.

When will the scheduled call or email take place?

You will need to be available for two calls or an email. The first call will collect your blood results and the second one will ask you a few questions around your warfarin dosage. A convenient date and time will be arranged with your clinician.

Don’t worry if you miss the call. It will try you three more times at half-hour intervals. An alert will be sent to the warfarin clinic if they are unable to make contact with you.

If you choose to receive an email rather than a phone call, you will need to respond to the first email between 5am and 12 midday. The return email with dosing instructions and the next test date can be accessed from 4pm to midnight on the same day.

To access the email service, you will be sent access documents in the post. You will need your NHS number, access code, username and password each time you log onto the system.

What are the benefits of the INR Self-Testing Service?

The home testing programme means you won’t have to travel to the clinic to be tested. Your results will still be reviewed by your clinician and you will still be able to contact them by telephone. You will be able to take your testing device with you to work, or on holiday. Just as long as you have a phone or email-capable device with you to share the results. The service is designed to make the lives of those on warfarin easier.

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I live in Gainford [a village in a rural part of Durham] and it’s eight miles either way to Barnard Castle Hospital, or Darlington, or Bishop Auckland to get to a clinic... It's much easier for me (self-testing).

They don’t have to come to hospital every two weeks, they don’t have to pay £2.50 for parking for that hour and sit in queues in the clinic, they don’t have to ask for time off work, they can go on their holidays to Spain or go off caravanning and still receive their warfarin dose from the nurses at County Durham and Darlington Foundation Trust.

Being able to self-test has given me a greater sense of freedom. For me, the biggest benefit is that I can go on holiday safe in the knowledge I can still manage my INR levels.

A number of our patients tell us that, when they come to clinic, they have to take the time as holiday. Self-testing gives them the freedom to test at home.


Leaflet – INR Self-Testing Service

Case study – INR Self-Testing Service

Patient leaflet – INR Self Testing Service

Video – NHS X INR