Point‐of‐care versus central laboratory testing of INR in acute stroke

Objectives Effective anticoagulant therapy is a contraindication to thrombolysis, which is an effective treatment of ischemic stroke if given within 4.5 hours of symptom onset. INR above 1.7 is generally considered a contraindication for thrombolysis. Rapid measurement of INR in warfarin‐treated patients is therefore of major importance in order to be able to decide on thrombolysis or not. We asked whether INR measured on a point‐of‐care instrument would be as good as a central laboratory instrument. Material and Methods A total of 529 consecutive patients who arrived at the emergency department at a large urban teaching hospital with stroke symptoms were enrolled in the study. INR was measured with a CoaguChek and a Sysmex instrument. Basic clinical information such as age, sex, and diagnosis (if available) was recorded. INR from the instruments was compared using linear regression and Bland‐Altman plot. Results Of 529 patients, 459 had INR results from both instruments. Among these, 3 patients were excluded as outliers. The rest (n = 456) showed good correlation between the methods ( R 2  = 0.97). In the current setting, CoaguChek was in median 63 minutes faster than Sysmex. Conclusion Our results indicate that point‐of‐care testing is a safe mean to rapidly acquire a patient's INR value in acute clinical situations.