Evaluation of Thrombi-Stat MC1 for whole blood and plasma international normalized ratio in comparison with a laboratory method

Abstract

Introduction: The precision and comparability of the international normalized ratio (INR) analyzed by the Thrombi-Stat MC1 coagulation testing system were evaluated before using as a point-of-care testing. Methods: Three levels of control materials were used for within-run and between-run precision study. Comparison study of INR determination from citrated whole blood (INR-WB) and citrated plasma (INR-PL) analyzed by the Thrombi-Stat MC1 with those by the validated method, Sysmex®CS-2100i (INR-CS), was performed. Results: The within-run coefficient of variations (CVs) of INR by the Thrombi-Stat MC1 were 3.60% to 4.80%. For between-run precision, the CVs were 4.26 to 4.93%. Fifty-four plasmas from patients receiving warfarin were included for comparability testing. There were good correlation and agreement between both INR-WB and INR-PL compared with INR-CS. Eighty-seven percent of INR-WB and 100% of INR-PL were within ± 0.5 units of the INR-CS. Given that the therapeutic range was INR-CS of 2-3, 3.7% of INR-WB and 5.56% of INR-PL were discordant with the INR-CS. Conclusion: The precision and comparability to validated method of the Thrombi-Stat MC1 were acceptable. Either citrated whole blood or plasma may be used as samples in this system. Impact on the management of patients must be taken into consideration prior to the implementation of this system. © 2012 Blackwell Publishing Ltd.