New quantitative aPTT waveform analysis and its application in laboratory management of haemophilia A patients.

Diagnosis of haemophilia A is usually made by the measurement of factor VIII (FVIII) activity that allows categorization of the disease severity. However, tests that assess global haemostasis may better reflect clinical features and give additional clinically relevant information. The aim of this study was to develop a new quantitative activated partial thromboplastin time (aPTT) waveform analysis and compare it with FVIII activities to find out whether waveform parameters are superior determinants of clinical phenotype. A total of 81 haemophilia A patients divided into two groups (37 severe, 44 non-severe) were included in the study. The control group comprised 101 healthy male volunteers. Quantitative aPTT waveform analysis was performed with Actin FS on BCS (Siemens Healthcare Diagnostics, Marburg, Germany) using three parameters (DELTA, RATIO-1, RATIO-2) obtained from a single aPTT measurement with two evaluation modes. FVIII activities were measured by one-stage clotting and two-stage chromogenic assay. Statistically significant difference (P < 0.001) between control group and all haemophilia A patients, as well as between severe and non-severe haemophilia A patients was obtained for all quantitative waveform parameters. Our study revealed parameter DELTA as the best waveform parameter, showing significant correlation with FVIII activities and clinical parameters, and excellent performance for distinguishing between severe and non-severe haemophilia A patients (ROC analysis: sensitivity 97.3%, specificity 93.2%). The results obtained by new quantitative aPTT waveform analysis were superior to those obtained by standard laboratory methods. The simplicity and cost-benefit of the method make this approach a reasonable and promising tool for assessing coagulation in haemophilia A patients.