Background: Current guidelines indicate that an INR > 1.7 is a contraindication to thrombolysis therapy in acute stroke patients. Guidelines also recommend a patient arrival-to-thrombolysis-start time of 60 minutes. However, assessment of INR in acute stroke patients can lead to treatment delay, if result turnaround time is prolonged. Point of Care (POC) coagulometers have been proposed as a potential solution, since they allow for rapid, bedside assessment of INR. Yet, POC coagulometers are susceptible to several pre-analytical and analytical variables and, data on the safety of these devices in the acute stroke emergency care setting are limited.

Aims: We sought to assess the reliability of POC-INR results relative to central laboratory-assessed INR (CL-INR).

Methods: We performed a retrospective review of all POC-INR results obtained in parallel with CL-INR over a 1-year period in acute stroke patients presenting to our emergency department.

Results: Thirty-eight parallel testing instances were identified. There was a strong positive correlation between POC-INR and CL-INR (P = 0.84). When the prothrombin time was within the normal range on the POC device (40% of cases), agreement with the CL-INR around the INR=1.7 cutoff for thrombolysis therapy was 100%. However, the POC prothrombin time was prolonged in 60% of cases with 16% of these having clinically significant disagreement with the CL-INR. In 3 cases, the POC-INR was >1.7 while the CL-INR was < 1.7. Likewise, in 3 other cases, the POC-INR was < 1.7 while the CL-INR was >1.7.

Conclusions: In 16% of cases, over a 1-year period, assessment of INR with a POC device alone could have led to the wrong treatment approach, potentially increasing the risk of adverse events in our emergency department acute stroke patients.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/clinically-significant-disagreement-between-point-of-care-inr-and-central-laboratory-assessed-inr-in-acute-stroke-patients/