Factor VIII Activity in Relation to the Type of Thrombosis and Patient's Risk Factors for Thrombosis, Age, and Comorbidity.

Objective: Elevated factor VIII has been shown to be an independent risk factor for deep venous thrombosis and pulmonary embolism. It has been suggested that increased factor VIII levels by itself is insufficient to cause thrombosis; however, increased factor VIII with other risk factors could increase the risk of thrombosis. The aim of the study was to evaluate the factor VIII level with regard to the type of thrombosis and patient's risk factors such as age or comorbidity.

Materials and methods: In total, 441 patients who were referred for thrombophilia testing from the period of January 2010 to December 2020 were included in the study. The patients who developed the first thrombosis before the age of 50 were eligible for the study. The patients' data that were used in statistical analyses were collected from our thrombophilia register.

Results: The number of the subjects with increased factor VIII over 1.5 IU/mL is equal regardless of the thrombosis type. Factor VIII activity already begins to increase over 40 years old and reaches the mean values of 1.45 IU/mL close to the cut-off (1.5 IU/mL), showing a statistically significant difference compared to those under 40, P = .001. Comorbidities other than thyroid disease or malignancy had no influence on the increase of factor VIII. In the mentioned conditions, the average factor VIII of 1.82 (0.79) and 1.65 (0.43) was obtained, respectively.

Conclusion: Factor VIII activity is significantly affected by age. Thrombosis type and comorbid diseases other than thyroid disease and malignancy had no effect on factor VIII.