The First-Derivative Curve of the Coagulation Waveform Reveals the Cause of aPTT Prolongation.

Clot waveform analysis based on activated partial thromboplastin time (aPTT) is reported to be a useful assay. We attempted to find beneficial parameters with the first-derivative curve. We examined 106 plasma samples with prolonged aPTT and analyzed the first-derivative curve statistically by dividing it into 6 groups (Lupus anticoagulant, Heparin, Direct oral anticoagulants, Factor VIII inhibitor, Hepatic dysfunctions and Factor deficiency). We obtained 7 coordinates for parameter measurement by analyzing the first-derivative curve and set 20 parameters including the velocity axis, the time axis, and area parameters. The distribution was checked by extracting each parameter that showed the most significant difference in the 6 groups. As a result, it was revealed that we could classify aPTT prolongation by using a combination of 3 parameters, the initial-to-peak gradient, the ratio initial-to-intermediate velocity/intermediate-to-peak velocity, and the initial-to-peak area size. We constructed a flowchart combining these 3 parameters and were able to discriminate 75% of the specimens. These parameters derived from the first-derivative curve of clot waveform analysis are useful tools to discriminate aPTT prolongation.