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

Abstract 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.