Points of Care Testing International Normalized Ratio: Are They Useful for Monitoring Vitamin K Antagonists in a Thrombosis Center?

Abstract Point of care testing (POCT) international normalized ratio (INR) devices are widely accepted for self-testing and self-management of vitamin K antagonists (VKAs). The aim of this work was to evaluate the performance of a POCT at our thrombosis centre aiming at reducing the time spent by patients for blood sampling and dose adjustment. A total of 101 consecutive oral anticoagulated patients (53 M, 48 F, median age 74 years, 23–89) were enrolled in the study that consisted of 2 different phases. In the first, standard monitoring was carried out for 3 months; during this period, the INR value was also determined by capillary blood sample with the use of a POCT to compare the INR values obtained with the two systems. In the second phase, patients were monitored for 3 months using only the CoaguChek XS Plus. The Bland-Altman test showed a good agreement between INR values obtained with the automated coagulometer and the CoaguChek XS Plus. The Passing and Bablok test showed no significant deviation from linearity. The total median waiting time was 3 hours and 45 minutes (from 0:44 to 6:05) and 1 hour and 16 minutes (P < 0.001) during standard monitoring and the use of the CoaguChek XS Plus, respectively. CoaguChek XS Plus is a suitable POCT for monitoring VKA therapy at a thrombosis centre, thus significantly reducing the time spent by patients for blood sampling and waiting for dosage adjustment.