Comparative analysis on characteristics of two activated partial thromboplastin time reagents

Area of Science:

• Clinical Chemistry
• Hematology
• Diagnostic Reagents

Background:

• Standardization of activated partial thromboplastin time (APTT) is lacking, leading to reagent-specific value discrepancies.
• Previous parallel measurements identified dissociated samples between Thrombocheck APTT-SLA and Coagpia APTT-n reagents.

Purpose of the Study:

• To identify factors contributing to ΔAPTT, the difference in measured values between two APTT reagents.
• To elucidate the mechanism behind reagent-dependent variations in APTT results.

Main Methods:

• Multiple regression analysis of 8324 samples using clinical laboratory data and APTT results.
• Spiking experiments with pooled plasma, target substances, and phospholipids to confirm identified factors.
• Assessment of reagent performance with varying concentrations of C-reactive protein (CRP) and phospholipids.

Main Results:

• Albumin-globulin ratio (AGR), CRP, hematocrit, and prothrombin time were identified as factors related to ΔAPTT (p < 0.001).
• C-reactive protein (CRP) addition caused pseudo-prolongation of APTT with Coagpia APTT-n compared to Thrombocheck APTT-SLA (p < 0.001).
• The observed prolongation due to CRP was mitigated by adding phospholipids, indicating an interaction.

Conclusions:

• The pseudo-prolongation of APTT is attributed to an interaction between CRP and phospholipids in the Coagpia APTT-n reagent.
• This interaction contributes significantly to the observed dissociation in APTT values between the tested reagents.
• Understanding these factors is crucial for accurate interpretation of APTT results in clinical practice.