Family history of venous thromboembolism and identifying factor V Leiden carriers during pregnancy

To estimate whether there is a correlation between family history of venous thromboembolism and factor V Leiden mutation carriage in gravid women without a personal history of venous thromboembolism.

This is a secondary analysis of a prospective observational study of the frequency of pregnancy-related thromboembolic events among carriers of the factor V Leiden mutation. Family history of venous thromboembolism in either first- or second-degree relatives was self-reported. Sensitivity, specificity, and positive and negative predictive values of family history to predict factor V Leiden mutation carrier status were calculated.

Women without a personal venous thromboembolism history and with available DNA were included (n=5,168). One hundred forty women (2.7% [95% confidence interval (CI) 2.3-3.2%]) were factor V Leiden mutation-positive. Four hundred twelve women (8.0% [95% CI 7.3-8.7%]) reported a family history of venous thromboembolism. Women with a positive family history were twofold more likely to be factor V Leiden mutation carriers than those with a negative family history (23 of 412 [5.6%] compared with 117 of 4,756 [2.5%], P<.001). The sensitivity, specificity, and positive predictive value of a family history of a first- or second-degree relative for identifying factor V Leiden carriers were 16.4% (95% CI 10.7-23.6%), 92.3% (95% CI 91.5-93.0%), and 5.6% (95% CI 3.6-8.3%), respectively.

Although a family history of venous thromboembolism is associated with factor V Leiden mutation in thrombosis-free gravid women, the sensitivity and positive predictive values are too low to recommend screening women for the factor V Leiden mutation based solely on a family history.