PB1139 - Establishment of a novel system based on clot waveform analysis for the quick differential diagnosis of activated partial thromboplastin time (aPTT)-prolonged plasma samples

Background: Prolonged aPTT is seen in coagulation factor deficiency, coagulation factor inhibitor, and lupus anticoagulant (LA) positivity and may require prompt differentiation. The cross-mixing test (CMT) is useful in differentiating among these disorders. We have previously applied clot waveform analysis to CMT (CWA-CMT) to develop a quantitative, rapid, and accurate method for differentiating factor (F)VIII deficiency, FVIII inhibitor, and LA. On the other hand, by applying template matching (TM) to the aPTT clot waveform, we have developed a method (CWA-TM) to determine FVIII deficiency without measuring FVIII activity. However, CWA-CMT was unable to determine individual deficient factors. In addition, the challenges with CWA-TM had the difficulty in differentiating FVIII deficiency from FVIII inhibitor and the misclassification of LA and hemophilia (H)A.

Aims: We aimed to construct a more accurate differentiation system in aPTT-prolonged samples by combining both CWA-CMT and CWA-TM.

Methods: Factor deficiencies (n=104; factors II, V, VIII, IX, XI, XII), LA positive (n=15), and coagulation factor inhibitors (n=20; factors V, VIII, IX) were used from patients’ plasmas and commercial plasmas. CWA was performed on the CP3000™ apparatus (SEKISUI MEDICAL) using Coagpia APTT-N (SEKISUI MEDICAL) reagent.

Results: In CWA-CMT, the sensitivity for factor deficiency, LA, and factor inhibitor was 100% (104/104), 100% (15/15), and 90% (18/20), respectively. Specificity was 94% (33/35), 100% (124/124), and 100% (119/119), respectively. Furthermore, CWA-TM was performed on plasma determined to be deficient in coagulation factors. As a result, severe HA (FVIII:C < 1%) was determined to be HA with a sensitivity of 100% (10/10) and specificity of 99% (99/100). Severe HB (FIX:C < 1%) was also determined to be HB with a sensitivity of 86% (6/7) and specificity of 99% (102/103).

Conclusion(s): The novel developed system contributes to the quick diagnosis of aPTT-prolonged plasma samples.