Performance of the microINR Point-of-Care System: A Multicenter Clinical Trial

There are limited publications about the microINR point-of-care (POC) system (iLine Microsystems). The current microINR POC system was compared with the ACL TOP 500 laboratory analyzer (Instrumentation Laboratory) and with the CoaguChek XS POC system (Roche Diagnostics).

This study was performed at three United States medical centers. Sixty-eight nonanticoagulated normal donors and 245 warfarin anticoagulated patients were included. Testing was performed in duplicate using capillary blood samples for the POC systems and venous blood samples for the laboratory testing. Accuracy and imprecision were assessed.

Comparing microINR to ACL revealed a correlation coefficient (r) of 0.973, a slope of 1.00 (95% confidence interval [CI], 0.97-1.03), and an intercept of 0.08 (95% CI, 0.04-0.15). When compared with the CoaguChek XS, r was 0.977 with a slope of 0.92 (95% CI, 0.89-0.94) and an intercept of 0.15 (95% CI, 0.08-0.19). Predicted bias values at international normalized ratio (INR) 2.0, 3.5, and 4.5 were ≤ 5% against both references. Agreement with ACL was 97, 95, and 100% for the INR ranges of < 2.0 ± 0.40, 2.0 to 4.5 ± 20%, and ≥ 4.5 ± 25%, respectively. Agreement for the combined INR ranges was 96% against ACL and > 96% against the CoaguChek XS. The coefficient of variation of the microINR was 5.03% for INR < 2.0 and 4.68% for the therapeutic INR range 2.0 to 3.5.

The microINR results demonstrate adequate imprecision and accuracy to both ACL and CoaguChek XS. This indicates that monitoring INR by this microINR POC system is reliable and acceptable for the management of warfarin therapy.