Role of family history in identifying women with thrombophilia and higher risk of venous thromboembolism during oral contraception

Background: Unrecognized thrombophilic defects increase the risk of venous thromboembolism (VTE) in women during oral contraception (OC). We evaluated the sensitivity and specificity of a family history of VTE to identify thrombophilia in women before OC and after venous thrombotic complications during OC. Methods: Thrombophilia screening was performed after obtaining a family history by means of a standardized questionnaire in (1) thrombosis-free women before OC and (2) women after an episode of VTE during OC. Results: We evaluated 479 thrombosis-free women before OC (age range, 15-49 years); family history was positive in 49 (10.2%). Thrombophilic defects were identified in 36 participants (7.5%; 95% confidence interval [CI], 5%-10%), 3 of whom had a positive family history (8.3%). The sensitivity and positive predictive value of family history of thrombophilic defects were 8.3% (95% CI, 2%-22%) and 6.1% (95% CI, 1%-17%), respectively. We also evaluated 189 women after VTE complications during OC (age range, 15-49 years); family history was positive in 48 (25.4%; 95% CI, 19%-32%), 22 of whom had a thrombophilic defect (45.8%; 95% CI, 31%-61%). Thrombophilic defects were identified in 81 women (42.8%; 95% CI, 36%-50%). The sensitivity and positive predictive value of family history of thrombophilic defects were 27.2% (95% CI, 18%-38%) and 45.8% (95% CI 31%-61%), respectively. Conclusion: Family history of VTE has low sensitivity and positive predictive value for identifying women with thrombophilia who are more susceptible to VTE complications during OC.