Waived PT/INR testing

We are currently using the CoaguChek XS system in our provider offices. We require that an INR result > 4.5 be confirmed with a venous specimen sent to the main lab. We have had several results that do not correlate well with the main lab instrumentation which uses Innovin. I was curious to see what other people are using for waived testing, and what your feedback is.


Thank you,


Replies to this Topic

Hi Cindy,

We use the CoaguChek XS Plus system.  We perform correlations twice per year.  Our correlations work well.  Our lab uses ACL Tops. 




We use the CoaguChek and the clinical Lab method is the Stago.  They do not correlate.  They wont since they have different ISI and different reagent types (human vs. rabbit).  What I do is monitor the actual versus expected Stago result on > 5.0 coaguChek Inr's to see if there is a positive bias in the difference between the expected and the actual to identify pre-analytical issues (tube over/underfilling, poor collection technique).

Hi Karen,

What cutoff do you have for your coagucheks that require a lab draw?  I am guessing it is >5.0.

We also currently have CoaguCheks and Stago and our working on getting comparisons completed and our lab inr cutoff updated.

How is it that you are monitoring actual versus expected stago results- is it possible for you to contact me with an example.  I would really appreciate it.

My email is brian.wittkop@sanfordhealth.org



We use the Coaguchek Plus for our Coumadin Clinic. We draw venous if >5.0 and have been going crazy over the fact that they don’t correlate with the Stago at our core lab. How are you supposed to dose a dvt Pt if you can’t compare correctly to another source?

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Hi Tammy, contact Dr. Corrine Fantz, director Scientific Affairs for Roche diagnostics Corporation.  corinne.fantz@roche.com  She helped us through this. 

Also, look up the article by Baker, W et al.  "POCT INR - Is It Adequate For Patient Care?".   Email me at Karen.updegraff@guthrie.org for more information.

I worked on my issue with the Coaguchek XS Pro and the Stago not comparing for months and found it to be so unacceptable that I had to pull the devices from testing. I also worked with Dr. Fantz and didn't get anywhere. My bias cutoff was INR greater than 3.0

How do you justify the bias between the two test platforms? What do you do when the Coaguchek reads an INR of 3.2 and the Stago is 2.6 and the provider is confused?

Thanks for your thoughts, I'm still trying to get this resolved.

Our system uses STAGO as central lab method and iSTAT PT-INR for POC.  There's also a lack of (acceptable) correlation with these two devices as well, as the result increases.  That said, we have opted to limit reportable range on iSTAT to 3.0 and block any result >3.0. 

From my experience PT/INR does not correlate when the INR is high. Over the years I did several studies and in my old job we made a cutoff of 2.5, you need a lab draw. We posted  a long comment  with every  POC INR result. It also included using the same method to monitor the INR.

Hello Cindy,

We use the Coaguchek XS in our Surgical Service department and in our Anticoagulation Clinics.  As the Coaguchek is a waived test we do not do correlations with the main laboratory.  Our critical is >5 at which point in SS we get a lab draw.  In the 2 years I've been here we have only  had 1 critical and it correlated with out IL (WERFEN) Tops analyzers.


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