In response to a question from Kim Kinney we posted the following “Quick Question” last week, “What is your critical INR call-out number?” The answers were relatively predictable…
We call out at…
INR 4.0: 10 (28.5%)
INR 5.0: 20 (57%)
INR 6.0: 3 (8.5 %)
We don’t report a critical INR: 2 (6%)
Total respondents: 35
These numbers seem consistent with my experience, however I’d like to provoke discussion with something I heard from Dave McGlasson at last week’s Bleeding and Thrombosing Diseases: 2008 Mayo Update in Rochester, MN. Dave’s group just published McGlasson DL, Romick BG, Rubal BJ. Comparison of a chromogenic factor X assay with INR for monitoring oral anticoagulation therapy.Blood Coagul Fibrinolysis 2008;19:513–7, and he said that while the chromogenic X correlated reasonably well with normal and therapeutic INRs, there was little correlation with INRs over 4.0.
In follow-up, have you found that INRs or 4.0 correlate well or poorly with clinical bleeding, and if so, does it call into question the practice of assigning a critical value? Please reply under “comments.”
Geo
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