Hyper-coagulability in obese patients accurately identified by combinations of global coagulation assay parameters

Routine laboratory methods are insensitive to hyper-coagulation, which may be detected by global hemostasis tests. Calibrated Automated Thrombogram (CAT) is a gold standard method to measure thrombin generation and coagulation potential. Thrombodynamics (TD) is a new global assay that monitors the spatio-temporal propagation of blood coagulation, separating initiation from amplification/propagation phases of coagulation and visualizing fibrin clot formation.

We investigated whether CAT and/or TD can identify hyper- and hypo-coagulable states in patients with well-characterized phenotypes and which parameters could be used as potential predictors of thrombotic risk.

Blood was collected from: (1) forty healthy volunteers; (2) twelve obese patients scheduled for bariatric surgery (BMI ≥ 35 kg/m²); (3) nine patients under therapy with vitamin K-antagonists (median INR 2.7); (4) eight patients treated with low molecular weight heparins (anti-Xa activity between 0.5 and 0.7 U anti-Xa/ml); (5) ten patients with hemophilia A or B. Tissue factor induced thrombin generation was measured with CAT. Propagation of thrombin generation and clot growth from a tissue factor coated surface were monitored with TD.

Thrombin generation and fibrin clot formation parameters were significantly higher in obese patients compared to healthy volunteers and anticoagulated or hemophilic patients. ROC analysis of combined CAT or CAT/TD parameters (integrating thrombin generation and fibrin clot formation) demonstrated an excellent accuracy in detecting hyper-coagulability.

Combinations of CAT assay parameters and of parameters of thrombin generation burst with final fibrin clot properties allow recognizing accurately hyper-coagulable plasma and may represent predictive markers for thrombotic events.