[Evaluation of CoaguChek XS for measuring prothrombin time in patients receiving long-term oral anticoagulant therapy].
BACKGROUND
Oral anticoagulation with warfarin requires routine monitoring of prothrombin time to maintain the international normalized ratio (INR) within the appropriate therapeutic range. Coagu- Chek XS (Roche Diagnositic, Germany) is a portable coagulometer that measures the INR. We evaluated the precision and accuracy of CoaguCheck XS by comparing it with CA-1500 (Sysmex, Japan).


METHODS
We analyzed the CV and the correlation of all INR results measured in 68 samples obtained from patients treated with warfarin and 10 samples from control subjects with no history of anticoagulant therapy with CoaguChek XS and CA-1500. We compared the turn-around time between two instruments and evaluated the differences between the results obtained with venous and capillary blood samples and those obtained with different lots of the test strip. We also evaluated the precision of the two instruments in 5 repeated tests with samples of normal and increased INR.


RESULTS
Mean INR values of 5 repeated tests with the same samples were similar. The correlation of INR values between two instruments was excellent (r2=0.97, P=0.001), and the difference in the values between the two instruments was mostly within the 95% limit of agreement, but was shown to increase in direct proportion to INR values. The turn-around time of CoaguChek XS was shorter than that of CA-1500. The differences between venous and capillary blood and between different lots of the test trip were not significant (P>0.05).


CONCLUSIONS
CoaguChek XS showed a good precision and correlation with CA-1500 with a very short turn-around time. This instrument should be clinically useful in monitoring INR of patients with oral anticoagulation.
Lee
Jae Hyeon
JH
Department of Laboratory Medicine, Chonbuk National University Medical School, Jeonju, Korea. cyk6772@chonbuk.ac.kr
Lee
Kyoung Suk
KS
Kim
Dal Sik
DS
Lee
Hye Soo
HS
Choi
Sam Im
SI
Cho
Yong Gon
YG
D000284:Administration, Oral; D000925:Anticoagulants / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D016903:Drug Monitoring; D006801:Humans; D019934:International Normalized Ratio / Q000295:instrumentation*; D011517:Prothrombin Time / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012648:Self Care / Q000295:instrumentation / Q000379:methods; D014859:Warfarin / Q000008:administration & dosage / Q000627:therapeutic use*
D000925:Anticoagulants; D014859:Warfarin