A combined approach using global coagulation assays quickly differentiates coagulation disorders with prolonged aPTT and low levels of FVIII activity

Patients with mild/moderate hemophilia (H)A, acquired HA (AHA) and lupus anticoagulants (LA), have prolonged aPTTs with low levels of factor (F)VIII activity, but the differentiation of these disorders is complex and time consuming. We established an approach to quickly differentiate these disorders using comprehensive coagulation tests. Patients' plasmas with mild/moderate HA, AHA, LA without anti-phospholipid syndrome [LA-APS(-)], and LA with APS [LA-APS(+)] were examined using clot waveform analysis (CWA) and thrombin generation test (TGT). Activated protein C (APC) sensitivity was assessed by TGT. CWA revealed similarly prolonged clot times in all groups [NP/mild/moderate HA/AHA/LA-APS(-)/LA-APS(+); 33 +/- 1/82 +/- 12/116 +/- 44/90 +/- 29/96 +/- 15 s] but significantly different decreased maximal coagulation velocity (3.1 +/- 0.1/1.3 +/- 0.3/0.9 +/- 0.5/1.6 +/- 0.3/2.2 +/- 0.5). In TGT, AHA group demonstrated severely reduced peak-thrombin levels (362 +/- 23/170 +/- 27/49 +/- 21/158 +/- 75/158 +/- 99 nM), whilst both LA groups markedly prolonged lag times (4.5 +/- 0.3/5.0 +/- 0.4/4.7 +/- 0.8/12.5 +/- 7.7/28.8 +/- 11.8 min), suggesting that AHA could be readily identified, but the different LA sub-types failed to be classified. An APC sensitivity demonstrated that 'normalized' APC-induced levels of peak thrombin in LA-APS(+) were significantly lower relative to LA-APS(-) (normalized %inhibition; 5 +/- 7/42 +/- 39 %). Our studies confirmed that %inhibition by APC was significantly decreased in NP preincubated with purified IgGs from LA-APS(+) compared to LA-APS(-), facilitating differentiation between LA groups. A combined approach using CWA and TGT could be a useful means of differentiating coagulation disorders with prolonged aPTT.