Normal hemostasis is a state of fine balance between procoagulant and anticoagulant factors in circulating blood. DVT is a condition with blood clot developed in the veins. The standard treatment for patients with acute DVT is anticoagulant therapy. Though new oral anticoagulants such as dabigatran, rivaroxaban, apixaban and edoxaban are as safe and effective as vitamin K antagonists (VKAs) , warfarin is still the most widely-used anticoagulant in the world and remains a viable oral anticoagulant for many patients because of its availability and cost . However, the anticoagulant activity of warfarin was affected by various factors, such as age, sex, body weight and genetic polymorphisms [15–18], it is not easy to maintain the target INR range. In previous study, we found that there is a higher dose of warfarin requirement in patients with non-O blood groups than O blood groups, the underling mechanism was not well known. Whether ABO blood type influences coagulation assays in patients with acute DVT remain to be determind.
Coagulation tests are widely used in clinic to detect abnormalities of hemostasis. The PT, APTT, TT, INR and fibrinogen are commonly performed coagulation tests. The reference intervals had minor variation with sex and age in healthy individuals  while. Blood lipids influence the values of PT but not APTT. Individuals with high triglyceride levels (≥ 200mg/dl) had shorter PT values than those with lower triglyceride levels . APTT was significantly prolonged in healthy with type O than those with type non-O while PT was not affected [10, 11]. A shorten APTT is associated with the risk of venous thromboembolism . However, in the present study, there are no differences about APTT among the A, B, AB and O blood groups. Furthermore the difference about APTT between blood group O and non-O was not significant, which suggested that the effect of ABO blood group on APTT varied with race.
PT is used to evaluate the extrinsic and final common pathways of coagulation, which is commonly used to monitor warfarin anticoagulant therapy. However, PT varied with the thromboplastin reagents and the instrument used in the laboratory, it is difficult to monitor warfarin anticoagulation and evaluate the anticoagulation effect of warfarin by PT. To correct for these differences, the INR was introduced. Initial INR before anticoagulation might have an influence on warfarin dose requirements. A lower value of initial INR would need more doses of warfarin when attaining the target INR. In the present study differences in INR between patients with different ABO blood groups were not significant, which suggested that the patients in the O blood group had lower warfarin dose requirements than those in non-O blood groups  was not associated with the initial INR.
Fibrinogen plays a key role in the blood coagulation system. Elevated plasma fibrinogen level is a risk factor for cardiovascular disease [22, 23]. Though fibrinogen was higher in patients with DVT than in controls , there were no significant differences in fibrinogen in patients with DVT for group O compared with group non-O blood group . In the present study, no differences were also found in patients among A, B, AB and O blood group. Moreover the difference about APTT between blood group O and non-O was not significant, which confirmed the previous report .
Apart from ABO blood group, the effects of sex and age on APTT have also been reported , with a significant higher APTT value in males than in females and negative correlation with age. However there was no significant difference about the influence of age and sex on APTT, suggesting the effect of age and sex on APTT also varied with race.
There were a few limitations in the present study. First, it was a retrospective study, unknown factors affecting coagulation tests can not be excluded. Second, the population of the study is small, large sample would be needed to verify the relations between APTT and ABO blood groups, sex and age in patients with acute DVT. Last, APTT varied with race , the association between ABO blood groups, sex, age and APTT in the Chinese Han population from the Chaoshan region may be different from that in populations from other races in China.
In summary, the present study demonstrated that coagulation tests were not affected by ABO blood group, age and gender in patients with acute deep vein thrombosis in the Chinese Han population from the Chaoshan region.