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Thrombin generation assay identifies individual variability in responses to low molecular weight heparin in pregnancy: implications for anticoagulant monitoring
Author(s) -
Chowdary Pratima,
Adamidou Despoina,
Riddell Anne,
Aghighi Saman,
Griffioen Anja,
Priest Paul,
Moghadam Lida,
Kelaher Nicholas,
Huq Farah Y.,
Kadir Rezan A.,
Tuddenham Edward G.,
Gatt Alex
Publication year - 2015
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/bjh.13193
Subject(s) - low molecular weight heparin , coagulation , medicine , pregnancy , anticoagulant , heparin , thrombosis , area under the curve , coefficient of variation , thrombin generation , thromboelastography , gastroenterology , thrombin , platelet , chemistry , chromatography , biology , genetics
Summary Low molecular weight heparin ( LMWH ) given to inhibit coagulation and reduce the risk of thrombosis, is typically monitored by anti‐Xa assay. However, anti‐Xa levels may not necessarily provide an accurate measure of coagulation inhibition. Moreover, pregnancy is associated with hypercoagulability, which may compromise the efficacy of LMWH . We looked at the association between anti‐Xa levels and parameters of thrombin generation assay [ TGA ; area under the curve ( AUC ), peak height ( PH ) and time to peak (ttP)] using samples from 41 pregnant women receiving LMWH and 40 normal pregnant women controls. TGA results confirmed the physiological hypercoagulability of normal pregnancy (mean normalised values: AUC 119%; PH 157%; ttP 72%). Although anti‐Xa measures correlated with all three TGA parameters, this group correlation masked significant inter‐individual variability, demonstrated by the R 2 value or coefficient of determination. Anti‐Xa levels contributed to 74% of variation in AUC values, 63% of variation in PH values and only 53% of variation in ttP values. The remainder reflects the contribution of patients’ intrinsic coagulation status. Hence, some patients with ‘safe’ anti‐Xa levels may potentially be under‐anticoagulated, particularly in pregnancy. Measuring coagulability directly with TGA may lower the risk of adverse events due to under‐anticoagulation in selected patients.