engleski

aPTT reaction curves provide important additional information in hemophilia patients

BACKGROUND: With modern coagulation analyzers, single activated partial thromboplastin time (aPTT) result is not just a number but a collection of photo-optical data in the form of a reaction curve. AIM: To investigate if aPTT reaction curve provides important additional information and whether it allows to predict the degree of FVIII/FIX deficiency from reaction curve in hemophilia patients. METHODS: The study examined plasma samples from 25 healthy, 89 hemophilia A and 17 hemophilia B subjects. aPTT (Actin FS, Atellica COAG360, Siemens, Germany) was determined with two evaluation modes: fixed absorbance (onset of coagulation, FA) and drifting baseline (DB) proposed by manufacturer. Moreover, aPTT at 50% coagulation (PI) was manually determined. We calculated DELTA-1 (aPTT-DB minus aPTT-FA) and DELTA-2 (aPTT-PI minus aPTT-DB). FVIII and FIX activities were measured by one-stage clotting assay and inhibitor using Nijmegen-Bethesda assay. Hemophilia A patients were further divided into HA1 (FVIII<1IU/dL, N=20), HA2 (FVIII=1-5IU/dL, N=22) and HA3 (FVIII>5-40IU/dL, N=47) groups, hemophilia B into HB1 (FIX= <1IU/dL, N=8) and HB2 (FIX≥1UI/dL, N=9) groups, and all hemophilia patients into 2 groups according to the presence (I2, N=29) or absence (I1, N=77) of an inhibitor. RESULTS: Results of DELTA-1 and DELTA-2 in all studied groups are presented in Table 1, whereas results of correlation between DELTA-1/DELTA-2 and FVIII/FIX activities are presented in Table 2. According to Receiver Operating Characteristic (ROC) analysis DELTA-1 >1.30 s allowed distinguishing between healthy and hemophilia subjects (sensitivity:100%, specificity:100%) and >3.64 s between patients with and without inhibitors (sensitivity:79.3%, specificity:53.2%). DELTA-2 values >5.90 s and >13.70 s allowed distinguishing between healthy and hemophilia subjects (sensitivity:93.4%, specificity:100%) and between patients with and without inhibitors (sensitivity:75.9%, specificity:74.0%). CONCLUSION: aPTT reaction curve provides important additional information in hemophilia patients. Parameters DELTA-1 and DELTA-2 can be reliable used to distinguish healthy from hemophilia subjects, as well as hemophilia patients with and without inhibitors.

aPTT reaction curves, hemophilia

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