Anticoagulation UK
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Warfain, self testing

For those of us on Warfarin who self test inr with their coagucheck machine, I believe their has been a problem with the test strips recently, so now maybe a good time to check your machine at the same time as a vein blood test

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It's a good idea to check your own Coaguchek with the machine at your GP surgery on a regular basis, to make sure that the results tally. It's not necessarily a good idea to compare your Coaguchek result with a venous sample, because capillary and venous blood behave differently - the two results may be the same, but they are also allowed to be different, by as much as 0.5. Your GP/nurse can give you more information.

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Hi yes I agree 0.5 is not a problem but from the sticky blood site on here some people are getting results of over 1.0 and even higher at the moment ? A problem with the strips so it a bit worrying

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I think that even the nurses have an issue too! I’m on INR testing with my local clinic and they’ve been doing an actual blood test the last 2 visits! Hope you get sorted.



There have been some reports of a possible problem. Every year the World Health Organisation change the calibration methods slightly. This seems to have caused some variations. Roche are aware and have issued a statement, see below. The Medicines Health and Regulatory Agency in the UK, MHRA, are investigating it and when they have results/answers they will publish them.

Roche statement.

We are aware that there have been a number of reports of variations (either higher or lower) in the INR values of CoaguChek test strips when compared to laboratory tests.

We have immediately initiated investigations and they are currently in progress.

Patient safety is of paramount importance to us and we pride ourselves on working to the highest quality standards.

If you have any concerns regarding a recent result, your condition or any other concerns, please contact your GP, nurse or pharmacist and call our Careline on 0800 100 7666 (UK) / 1 800 99 2868 (Ireland) (or send an email to


Hi DaisyD/All,

Interesting, I have self-tested for three years or so and during the last six to nine months and perhaps coincident with a new batch of test strips, my readings have been all over the place (from 2 to 5) against a target INR of 3. As a result my anticoag clinic has been insisting on fortnightly (at times weekly) tests.

During this time I've had the annual calibration check/venous comparator and the variance was 0.6.

Empedrola - Do you know when the Roche statement was issued and whether specific batch numbers/ranges are under suspicion? Thanks TC


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