Differences in the Composition of Activated Partial Thromboplastin Time (APTT) Reagents Affect Clot Waveform Analysis

Area of Science:

• Hematology
• Clinical Chemistry
• Diagnostic Assays

Background:

• Clot waveform analysis (CWA) using activated partial thromboplastin time (APTT) is a valuable hemostasis assay.
• The influence of activators and phospholipid conditions on CWA requires further investigation.
• This study aimed to characterize CWA using various APTT reagents.

Purpose of the Study:

• To investigate the impact of different activated partial thromboplastin time (APTT) reagents on clot waveform analysis (CWA).
• To compare key waveform parameters across various APTT reagents in different patient groups.

Main Methods:

• CWA was performed on plasma samples from healthy individuals, hemophilia A (HA) patients, and HA patients on emicizumab treatment.
• Four distinct APTT reagents (A, B, C, and D) were utilized for the analysis.
• Key parameters including clotting time (CT), Ad|min1|, Ad|min2|, and Ad|max2| were compared.

Main Results:

• Clot waveform shapes were consistent within each reagent group but differed across patient cohorts.
• Significant variations were observed in CT, Ad|min1|, Ad|min2|, and Ad|max2| among the reagents.
• Reagent D, containing silica and synthetic phospholipids, demonstrated the fastest coagulation reaction.

Conclusions:

• The composition and concentration of APTT reagents significantly influence CWA parameters.
• Inter-reagent variability complicates the standardization of quantitative CWA evaluations.
• Understanding reagent-specific characteristics and establishing facility-specific reference ranges are essential for accurate CWA interpretation.