This study aimed to evaluate the cause of thrombosis in Behçet's disease (BD) patients, since
abnormalities in coagulation and fibrinolytic parameters have shown contradictory results. Methods: Haemostatic
parameters were retrospectively evaluated in BD patients treated between January 2007 and January 2011 at Sultan
Qaboos University Hospital, Oman. The blood samples of 35 Omani BD patients and 30 healthy controls were
analysed for factor VIII:C levels, activated protein C resistance (APCR), von Willebrand factor (vWF) antigens
(Ag), collagen binding and ristocetin co-factor activity (RiCoF), antithrombin (AT), protein C (chromogenic and
clotting), protein S, homocysteine, tissue plasminogen activator, plasminogen activator inhibitor, plasminogen,
alpha 2-antiplasmin, lupus anticoagulant and anticardiolipin and beta2-glycoprotein-1 antibodies. Results: The
mean values of factor VIII:C, vWF Ag, AT and protein S were significantly higher in the patient group (P = 0.01,
0.006, 0.04 and 0.01, respectively). There was no deficiency in protein C. Screening for APCR, anticardiolipin
antibodies, anti-beta2-glycoprotein-1 antibodies and lupus anticoagulant was negative and there were no differences
in homocysteine levels, nor were there differences between patients with and without thrombosis. Six patients had
elevated factor VIII:C levels (>150 IU/dL, P <0.02) which normalised on repeat measurements after three months.
Conclusion: The elevation of factors VIII:C, vWF Ag and AT most likely represent an acute phase phenomenon.
In this study, thrombophilic factors did not seem to explain thrombotic tendency. Therefore, further mechanistic
studies in a larger group of patients are needed to elucidate the basis for thrombosis in BD. We hypothesise that
active BD causes vasculitic endothelial perturbation with dysfunction, leading to the observed increased propensity
for thrombosis.