Comparability of Pathromtin SL, Dade Actin FS i STA Cephascreen reagents for activated partial thromboplastin time measurement

Aim: Aim of the study was to investigate correlation of activated partial thromboplastin time (APTT) measured with three different reagents: Pathromtin SL and Dade Actin FS reagents on Berichrom Coagulation System analyzer, and by STA Cephascreen reagent on STA Compact analyzer. Material and methods: APTT was determined in parallel by Pathromtin SL and Dade Actin FS reagents, and by STA Cephascreen reagent in 114 fresh plasma samples from subjects administered low-molecular-weight heparin and in subjects known to receive no anticoagulant therapy. APTT values were determined by coagulometry method immediately upon the material receipt at coagulation laboratory. AFT values were also determined in Bio-Rad Lypocheck Coagulation Control samples (Bio-Rad Laboratories, USA) covering three different value ranges. Results: The values recorded in Bio-Rad controls were within the range declared by the manufacturer for all three reagents used. Correlation of APTT values obtained by use of Pathromtin SL vs. Dade Actin FS, Pathromtin SL vs. Cephascreen and Dade Actin FS vs. STA Cephascreen yielded strong correlations (R = 0.9485, 0.9353 and 0.9072, respectively). A statistically significant difference was recorded between the results obtained by Pathromtin SL and Dade Actin FS reagents. Passing-Bablok regression slope and y-axis intercept included 1 and 0 only for Dade Actin FS vs. STA Cephascreen. Conclusion: Study results showed the best compliance of values obtained by Dade Actin FS and STA Cephascreen reagents. In spite of strong correlations, Passing-Bablok regression indicated lower comparability between Pathromtin SL and Dade Actin as well as between Pathromtin SL and STA Cephascreen reagents, As the study results confirmed the observations from daily routine, it is of utmost importance that individual patients receiving heparin therapy be not monitored by use of different reagents due to the variable reagent sensitivity to low molecular weight heparin.