Caroline - I don't want this to devolve into a string of unpleasantness.
I'm not necessarily 'bashing' the people who are doing the testing - I don't know them.
I'm not using the 'same meter' that this clinic is probably using. I use the Coag-Sense. I wouldn't be particularly comfortable if the clinic was using the same meter as the one that I use at home -- and here's the reason: there are blood issues (hematocrit and others) that would make the CoaguChek XS give erroneous results. These are well documented. If a person has this blood condition, testing with CoaguChek XS at home and at the lab would result in the same erroneous value. Personally, I'd have more confidence in my INR if a different method was used to check it -- that way, you can avoid any anomalies that may make a meter give a bad result. If you have a problem, using the same meter wouldn't reveal it.
And testing every two or three weeks is NOT advised. A clot can form in as little as ten days - testing every two or three weeks wouldn't detect when your INR drops below 2.0. Three weeks is NOT fine. Two weeks is NOT great if 'you have the same reading' - although, I must confess, my INR is usually pretty consistent, and I sometimes go two weeks between tests, but still get a bit nervous after a week or so.
These 'good people' may be working from old information -- recent papers have shown that patients who self-test weekly show the most time in range. Maybe your 'good people' didn't see that.
Personally, I wouldn't wait two or three weeks to test - if you have a meter, it's strongly advised to test weekly - and if it makes you feel better, go to your lab for your test every two or three weeks.
One more thing -- you can't assume that the meter's results are more accurate than the lab results. Although I've recently run across some labs that do an extremely inaccurate reading, most of the readings have been very accurate. They don't do these in labs because they're inaccurate (although they sometimes are).
Testing at a lab, or with a meter isn't an exact science - it relies on how the blood is handled, the reagent used, and perhaps other factors. The testing method (tilt tube) used by the labs detects formation of an actual clot. CoaguChek XS uses a method that reads electrical changes and computes an INR and prothrombin time (probably less accurate than labs, but accurate enough for the purposes of INR management). Coag-Sense uses a mechanical method for detecting clots, similar to the way that labs do it.
Labs take longer. You have to get a larger sample of blood drawn from the arm. The results are often reported in decimals to two places (i.e. 2.35). When done right, they're more accurate than a meter.
And, FWIW, I'm not bashing any of these anonymous, unidentified people as individuals - I point out when I don't think you're getting the care (and protection) that you should be getting. I don't know WHO they are. I'm not making this a personal attack - and I don't know why you perceive it to be one.
