CoaguChek INR patient correlations
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I have a Roche CoaguChek XS Pro that I use for INR's in our Anticoagulation clinic. It is used by the pharmacists, and it has been in use for over 7 or 8 years. I run patient correlations every 6 months against our Main Lab Werfen TOPs 500 analyzer. I have been able to get these two to correlate within 15% for all of these years and on my current correlation I ran, I had over half of my patients not correlating well. I have called Roche and they sent new lot of strips and I still have a discrepancy. It isn't on every patient ran, but these are disturbing since the difference is enough to make a difference in medication changes. I have 4 different CoaguCheks and they are correlating to each other; all QC and CAP surveys have all been acceptable for both the CoaguCheks and the TOPs analyzer. Both methods use a Human Recombinant Thromboplastin, Roche tells me that they are two different methods and can't really compare. They feel if the QC is in there shouldn't be any problems. Does anyone have advice or had any problems with the CoaguChek strips?
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Does this CoaguChek report out waived or moderate complex results?
CAP does not require correlations between waived tests and moderate complex tests.
**REVISED** 12/26/2024
COM.04250 Comparability of Instruments and Methods - Nonwaived Testing Phase II
This requirement is not applicable to:
● Calculated parameters
● Waived methods
● Laboratories with different CAP numbers
● Instruments/equipment that do not provide a reportable result (eg, microscopes, stainers)
I also have the moderate complex CoaguChek with the barcode reader and I have a heck of a time getting it to correlate with our Stago. It seems to correlate well with "normal" PT/INR. I use Roche's FDA clearance criteria to validate the method if that makes sense.
I work for Stago as a scientific marketing manager, and would like to state there is usually acceptable correlation between any INR platform (POC or lab) within the warfarin therapeutic range, along within the normal range, but outside of those ranges there should be no expectation of acceptable correlation. This is partially due to different platforms using mechanical vs. optical, recombinant vs. tissue extract PT reagent, ISI, etc. but a very big factor is that manufacturers can only perform validation of their products using plasma materials up to INR 4.5. There is no way to validate any platform above this value, due to INR testing plasmas only being available up to that value. It is unethical to collect plasma from patients with INR values above 4.5 due to the significant bleeding risk above that INR value. Instead, institutions should perform their own sufficiently powered correlation between methods used and develop a cutoff for which the POC result should be reflexed to the main lab with a venipuncture result. Usually in my experience that value is 3.5, 4.0, or 4.5, depending on the quality of the dataset. I can send anyone peer-reviewed literature describing these issues further if you reach out to me at paul.riley@us.stago.com.