Secondary Logo

Journal Logo

Institutional members access full text with Ovid®

Extrapolation of the R-T Estimation in CoaguChek International Normalized Ratio Results Below 4

Richter, Christopher, PharmD, BCPS

doi: 10.1097/POC.0000000000000189
Original Articles

While extensive literature has documented that the CoaguChek XS device results are not an accurate reflection of a patient's international normalized ratio (INR) when the values are elevated, only 1 equation has been able to consistently correct these results in the clinical setting. Data obtained from a previous study were used to apply the R-T Estimation to INR values below 4 to assess an extrapolation of this equation to an INR of 1. The results were consistent with previous studies using the R-T Estimation and demonstrate the correlation of this equation with venipuncture results with 95% confidence within 20% difference. This may be clinically relevant as a CoaguChek XS result of 3.8 is corrected using the R-T Estimation to an INR of 3.0.

From the Haven: Advanced Illness Care, Gainesville, FL.

Reprints: Christopher Richter, PharmD, BCPS, 4200 NW 90th Blvd, Gainesville, FL 32606. E-mail:

The author declares no conflict of interest.

Sources of support: CoaguChek XS machines are used in the UF Health hematology anticoagulation clinic and were provided to the clinic with the purchase of bulk supplies of test strips. There is no bias that will affect the laboratory results and data collection.

Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved