Comparison of two coagulometers for the determination of activated partial thromboplastin time, prothrombin time and thrombin time

Arjit Tiraganjana, Katcharin Aryurachai, Pantep Angchaisuksiri


Activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) are useful tests for detecting abnormality of coagulation factors involved in coagulation cascade and mornitoring anticoagulant levels. The aim of this study was to compare two electric-mechanical coagulometers in our laboratory, KC4A (Amelung, Germany) and ST4 BIO (Diagnostica Stago), whether the instruments would give different APTT, PT and TT results. The study was performed in 100 patients’samples sent to the Hematological Division, Department of Pathology, Faculty of Medicine, Ramathibodi Hospital for coagulation study. Normal control plasma was also analyzed for precision study. The results demonstrated that the mean values of APTT, PT and TT performed by the two instruments in normal control plasma were similar. Range of Coefficient of variation (CV) of within-run precision was 1.29%-2.23% and that of between-run precision was 1.8%-5.04%. The comparison study using 100 patients’ samples indicated correlation between the instruments and r values were 0.994, 0.996 and 0.992 for APTT, PT and TT, respectively (p <0.001), revealing linear regression curves (p<0.0001). There were no significant differences of the mean values of APTT (p=0.43), PT (p=0.29) and TT (p=0.40). In conclusion, both KC4A and ST4 BIO coagulometers gave high result preci- sion and there is no differences in the determination of APTT, PT and TT especially for mornitoring of anticoagulants. Thus, we can use one as a substitution for the other.

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