Relevance of Inherited Risk Factors in Young Patients with Deep-Vein Thrombosis

The relevance of congenital thrombophilia in the pathogenesis of venous thromboembolism in young patients is still debated. In a case-control study, plasma antigen and activity of antithrombin, protein C, and plas minogen, as well as total and free protein S were mea sured in a series of 166 consecutive outpatients aged less than 50 years, who underwent contrast venography be cause of clinically suspected deep-vein thrombosis (DVT). The presence of major acquired risk factors for venous thrombosis was also recorded. The association between DVT and inherited thrombophilia or acquired risk factors was initially described using crude odds ratios (OR). Subsequently, a logistic regression model was used to test their independence. Of the 166 patients included, venography showed an acute DVT in 73 (cases), whereas it was normal in the remaining 93 (controls). Major ac quired risk factors were identified in 51 cases and in 20 controls (crude OR: 8.5; 95% CI: 4.1-17.1). Inherited thrombophilia was detected in seven cases and in one control (crude OR: 9.8; 95% CI: 1.2-81.2). Inherited thrombophilia was equally distributed between patients with secondary and idiopathic DVT and was proved to be independent from acquired risk factors in the regression model. Inherited thrombophilia is an independent risk factor for DVT in young patients. However, its preva lence in unselected cases with the first episode of DVT is low.