Clot waveform analysis potentially provides predictive information on the sensitivity of activated partial thromboplastin time reagents to lupus anticoagulants

Background: While previous studies have assessed the clinical values of clot waveform analysis (CWA) for detecting lupus anticoagulants (LA), there are no reports focusing on whether CWA predicts the LA sensitivity of activated partial thromboplastin time (APTT) reagents. The present study aimed to assess the usefulness of CWA in evaluating the LA sensitivity of APTT reagents. Methods: Commercially available pooled normal plasma (PNP) and LA-positive plasma control (LPC) were used. CWA findings were compared among nine APTT reagents. Results: Waveform abnormality appeared in assays with six APTT reagents for LPC but not for PNP. No waveform abnormality was evident in assays with three reagents for LPC or for PNP. In assays using reagents exhibiting waveform abnormality, APTT for LPC was longer and ratios of APTT for LPC/APTT for PNP were higher. Waveform abnormality was associated with indexes for evaluating mixing tests. Quantitative evaluation regarding the reduction of CWA parameters adjusted to compensate the influence of fibrinogen was likely applicable for predicting the LA sensitivity of APTT reagents. Conclusion: The present study suggested the usefulness of CWA for evaluating the LA sensitivity of APTT reagents. The results provide insights into use of APTT reagents for LA screening.