Correlations between clot waveform analysis parameters and fibrinogen concentrations in cases with and without prolonged activated partial thromboplastin time or prothrombin time

BACKGROUND: Clot waveform analysis (CWA) is performed to extend the interpretation of clotting reaction curves in activated partial thromboplastin time (APTT) or prothrombin time (PT) assays. The present study aims to investigate the relationship between CWA parameters and fibrinogen concentrations for elucidating how to use CWA for coagulation assessment. METHODS: Data regarding APTT-CWA, PT-CWA, and fibrinogen measurements were analyzed from 83 different individuals with prolonged APTT or PT and from 145 different individuals with APTT and PT within their reference ranges. CWA was adjusted to cancel out the influence of fibrinogen. RESULTS: The coefficient of variation (CV) was much lower in adjusted CWA parameters than in non-adjusted CWA parameters, concordant with canceling out the influence of fibrinogen concentrations. The CV in adjusted CWA parameters was higher in cases with prolonged APTT or PT compared to those with normal APTT and PT, likely due to the presence of various coagulopathies and anticoagulants. Regardless of APTT or PT data, non-adjusted CWA parameters and non-adjusted/adjusted CWA parameter ratios were positively correlated with fibrinogen concentrations. In APTT-CWA, the correlation coefficients of non-adjusted/adjusted CWA parameter ratios with fibrinogen concentrations were lower in cases of prolonged APTT or PT than in cases with normal APTT and PT, suggesting that other determinants than fibrinogen concentrations may alter turbidity changes and affect the CWA. CONCLUSION: The present study demonstrated correlations between CWA parameters and fibrinogen concentrations in clinical samples. The results are expected to help broaden the interpretation of clotting reaction curves in APTT and PT assays.