Overall hemostasis potential and aPTT‐clot waveform analysis as powerful laboratory diagnostic tools for identification of hemophilia A patients with unexpected bleeding phenotype

Abstract

Introduction Traditionally used laboratory methods do not always accurately reflect bleeding severity in hemophilia A (HA) patients. The ability of three global assays for identifying patients with unexpected bleeding phenotype was investigated. Methods Overall hemostasis potential (OHP), aPTT‐clot waveform analysis (aPTT‐CWA), endogenous thrombin potential (ETP), FVIII activities, and prothrombin fragment 1 + 2 concentrations were measured in 62 HA patients (30 severe and 32 non‐severe) and 27 male controls. Bleeding phenotype was determined using our proposed scoring system including age at first joint bleed, number of target joints, and number of joint/muscle bleeds per year. Bleeding score ≤ 4 defined patients with mild bleeding phenotype (N = 27); score ≥ 5 defined severe bleeding phenotype (N = 35). Results The receiver operating characteristic analysis performed for distinguishing patients with severe and mild bleeding phenotype yielded following values of area under the curve: 0.910 (FVIII); 0.891 (aPTT‐CWA parameter DELTA); 0.769 (OHP); and 0.634 (ETP). Unexpected bleeding phenotype was identified in 11/62 HA patients: 8/32 (25%) non–severe HA patients had severe, while 3/30 (10%) severe HA patients had mild bleeding phenotype, and global assays enabled the identification of all these patients. OHP and DELTA were revealed as the most reliable parameters for bleeding phenotype determination (10/11 and 9/11 unexpected results, respectively). Conclusion This study emphasizes OHP and aPTT‐CWA as a powerful laboratory diagnostic tool in identifying HA patients with unexpected bleeding presentations, with the best results achieved by combining both assays. Global assays should not completely replace FVIII activity measurement but should be a part of the HA diagnostic algorithm.

Comparison of analytical performances between clot waveform analysis and FibWave in edoxaban‐treated patients and healthy controls

“…This technique is of interest for several coagulation abnormalities. 28 , 29 , 38 , 39 Recently, our group developed a new series of tests with improved sensitivity compared to traditional CWA, namely, the FibWave. In vitro results showed encouraging performances of this methodology and reveals its high sensitivity toward prothrombotic tendencies and anticoagulant status.…”

“…For several decades, a particular attention has been focused on additional parameters extracted from aPTT‐ and PT‐CWA, allowing to consider this latter as a global coagulation assay. This technique is of interest for several coagulation abnormalities 28,29,38,39 . Recently, our group developed a new series of tests with improved sensitivity compared to traditional CWA, namely, the FibWave.…”

“… 27 Abnormalities in clot waveforms have already been used for the diagnosis and the prognosis of different coagulopathies. 20 , 21 , 28 , 29 , 30 , 31 …”

Advances in laboratory assessment of thrombosis and hemostasis

“…Clinically, min1 was used to assess the effects of emicizumab and/or bypassing agent in various subgroups of hemophilia A [ 20 - 22 ]. Beyond pharmacodynamic studies, CWA was a useful screening tool for hemophilia A [ 23 ]. Furthermore, FVIII specific inhibitors were easily differentiated from lupus anticoagulants when mixing APTT data was interpreted by CWA [ 24 ].…”

Thromboelastography and thrombin generation assessments for pediatric severe hemophilia A patients are highly variable and not predictive of clinical phenotypes

“…19 In vitro hemostasis assays have long been featured in the diagnosis, management, and physiological study of bleeding disorders, owing to the insights they provide into hemostatic function. [20][21][22][23][24][25] For example, thrombin generation assays have been used to examine factor activity levels and bleeding severity in adult HA patients 26 and patients with other rare bleeding disorders, 27 and to monitor the pharmacokinetics of FVIII 26 and the response of SHA patients to FVIII-bypassing agents [28][29][30][31] and emicizumab. 32 Such studies have primarily used calibrated automated thrombography (CAT), which allows accurate high-throughput testing of both platelet-rich plasma (PRP) and platelet-poor plasma (PPP).…”