African-Caribbean ethnicity is associated with a hypercoagulable state as measured by thrombin generation.

African-Caribbean ethnicity is associated with an increased risk of both first and recurrent venous thromboembolism (VTE). The aim of this study was to evaluate thrombin generation in African-Caribbeans compared with whites in patients with deep vein thrombosis (DVT) and healthy volunteers. Thrombin generation was measured in a case-control study of 80 patients who had completed anticoagulation therapy for a first DVT (50 white and 30 African-Caribbean) and 66 controls. Peak thrombin with and without thrombomodulin was significantly higher in African-Caribbeans with DVT compared with whites with DVT (P < 0.001 for both comparisons) and African-Caribbean controls (P < 0.001, 0.003, respectively). Endogenous thrombin potential (ETP) with and without thrombomodulin was significantly higher in African-Caribbeans with DVT than whites with DVT (P ≤ 0.001 for both comparisons). Maximum velocity and ETP ratio were increased in African-Caribbeans with DVT compared with whites with DVT (P < 0.001 and 0.030, respectively) and African-Caribbean controls (P < 0.001 and 0.019, respectively). Within the control group, peak thrombin was significantly increased in African-Caribbeans compared with whites (P = 0.017). ETP, peak thrombin with thrombomodulin and maximum velocity were also increased in African-Caribbeans compared with white controls (P = 0.045 for all comparisons). African-Caribbeans with DVT had significantly higher factor VIII levels compared with whites with DVT and controls. African-Caribbean ethnicity confers a hypercoagulable state as measured by thrombin generation. This supports epidemiological findings of increased risk of first and recurrent VTE. Thrombin generation requires adjustment for ethnicity in studies undertaken in ethnically diverse populations.