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Discrepancies between APTT results determined with different evaluation modes on automated coagulation analyzers
M Milos1, D Coen Herak, R Zadro
1Clinical Institute of Laboratory Diagnosis, Zagreb Clinical Hospital Center and University School of Medicine, Zagreb, Croatia.
International Journal of Laboratory Hematology
|May 8, 2010
Summary
Different evaluation modes significantly impact activated partial thromboplastin time (APTT) results. Visual inspection of reaction curves is crucial for confirming the accuracy of APTT testing, especially when using the point of inflexion mode.
Area of Science:
- Clinical Chemistry
- Hematology
- Medical Diagnostics
Background:
- Photo-optical coagulometers generate reaction curves to determine clotting times.
- Various evaluation modes can be applied to analyze these curves, potentially influencing results.
Purpose of the Study:
- To assess the impact of different evaluation modes on activated partial thromboplastin time (APTT) results.
- To explore the benefits of visually inspecting reaction curves for result validation.
Main Methods:
- Activated partial thromboplastin time (APTT) was measured in 174 plasma samples using Actin FS reagent.
- Three evaluation modes (Fixed Absorbance, Drifting Baseline, Point of Inflexion) were tested on two different coagulometers (Behring Coagulation Timer and Behring Coagulation System).
Main Results:
- Statistically significant differences in APTT results were observed between the Point of Inflexion mode and other modes across both analyzers (P<0.0001).
- These variations highlight the need for analyzer-specific reference intervals based on the chosen evaluation mode.
Conclusions:
- Laboratory professionals must be aware of the influence of evaluation modes on APTT results and analyzer differences.
- Visual analysis of reaction curves is essential for verifying the correctness of reported APTT values.
