Coag-Sense machine - discrepancies with lab

[KLS39]

I started doing at home testing three months ago. It has been a bit of a struggle. My INR results started dropping compared to what my lab results had been for the previous 2-3 months. I'm guessing it was my technique which has gotten better. In December I tested at home (1.6) and then the lab within an hour (1.8). At the same time, I was working with the cardiologist's office to increase my INR to the top of my range (range in 1.5 - 2.0). My INR wasn't increasing as I expected so I did another comparison in January. At home 1.5 and lab 2.0. I was still struggling getting a good sample, getting it the tube and getting it in the machine so I thought it was my technique. Today I felt much more confident in my technique and was a 2.0 at home (finally) but also had scheduled an appointment at the lab which was 2.5. Is it concerning to have this large of a discrepancy? I've reached out to the company that provided the device and they will get back to me tomorrow.

 

[pellicle]

Hi

. Today I felt much more confident in my technique and was a 2.0 at home (finally) but also had scheduled an appointment at the lab which was 2.5. Is it concerning to have this large of a discrepancy?

what was the delay between samples? If less than a few hours then that's not to blame.

its larger than I'd like but then I don't like the coagsense ... it seems fiddly. As to the difference I'd say that its a "safe" difference as 0.5 under on the side of the CS is only going to encourage you to move up a little. No harm there. Remember the aim of INR is to not have any bleeding or thrombosis episodes. Its not an exact science and I've seen bigger differences than that between labs.

Note: I have not used one, they are not common (never heard of even one) in Australia.

 

[KLS39]

I was at the lab within an hour each time that I have compared my at home test to the lab.

 

[tom in MO]

One way to look at it is through measurement error. If the home and lab can be +/-0.2INR, than a difference of 0.4 is within measurement error and 0.5 is pretty close. Another way to look at it is through bias. If your home meter is biased low, then there is no risk that you won't be above therapeutic INR to avoid a clot.