Abstract
Introduction 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).
Methods 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.
Results 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.
Conclusion 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.
Keywords
international normalized ratio - warfarin - point-of-care systems - anticoagulants
- prothrombin time
