Haemostasis Assessed by Rotational Thromboelastometry and Thrombin Generation Test in Behcet's Disease Patients,

Behçet's disease (BD) is a chronic inflammatory disease of unknown etiology associated with an increased risk of venous and arterial thrombosis. To date, no studies for haemostasis have been conducted in this population by rotational thromboelastometry and thrombin generation test. These methods appear to be more sensitive and specific than routine coagulation tests in detecting defects of the coagulation system and could provide new elements for better understanding the mechanisms involved in the hypercoagulable state observed in BD patients. On this basis, this work aims to study haemostasis in patients with BD by rotational thromboelastometry (ROTEM ®) and thrombin generation test (CAT).

Twenty-six patients with BD were included. Ages were between 25–86 years (mean ± SD: 48.60 ± 15.66 years) and 73% were female. Eight patients had active disease at the time of enrollment and 6 had a history of thrombosis. Control group included 20 healthy individuals aged between 28–55 years (42.85 ± 9.02 years) and 65% were female.

Rotational thromboelastometry was performed in whole blood with ROTEM® coagulation analyzer (Pentapharm, Munich, Germany) at INTEM condition (activation of coagulation mainly throughout intrinsic pathway). Samples were allowed to rest 1 hour at room temperature and heated for 4 minutes at 37 ° C immediately before testing.

Thrombin generation was measured in platelet-free plasma by the method of Hemker (Calibrated Automated Thrombography, CAT). Activation was performed with a final concentration of 4 mM of phospholipids and 1 pM of tissue factor which favored the activation of coagulation mainly throughout intrinsic pathway.

Normal distribution for continuous variables was assessed with the Shapiro-Wilk testComparisons of quantitative variables were made with non-paired Student's t-test or Mann-Whitney's U test as appropriate.

Values of thromboelastometry parameters were increased in samples from BD patients. The higher clot consistency at 5 and 10 minutes (p=0.0452 and p=0.0179 respectively), and the pronounced maximal clot firmness (p=0.0064) suggest that platelet function may be altered in our patient cohort. Moreover, values higher than control ones for a angle (p=0.0266), maximum clot formation velocity (p=0.0454) and area under the curve at 5 and 10 minutes (p=0.0206 and p=0.0220 respectively) point to an increased thrombin generation in BD patients. In order to verify this hypothesis, thrombin generation was evaluated in samples from these patients. CAT experiments showed that BD patients had an increased endogenous thrombin potential (p = 0.0251) and reached higher maximum levels of thrombin (peak height, p = 0.0119) than controls.

To determine if haemostatic profile in BD patients evaluated by rotational thromboelastometry and CAT correlates with disease activity, Spearman's rank correlation coefficient was calculated. There was a significant but mild correlation between disease activity and area under the curve at 5 minutes (r=0.3818, p=0.0494) and the maximal clot firmness (r=0.3978, p= 0.0399) (thromboelastometry parameters) and the peak height (r=0.4615, p=0.0251) (CAT parameter).

Rotational thromboelastometry at INTEM condition and thrombin generation test confirmed that there is a hypercoagulable state in Behcet's disease. Procoagulant/anticoagulant protein equilibrium and platelet function may be altered in this pathology as indicated by several parameter measured by both tests.

No relevant conflicts of interest to declare.