Synergism between non-O blood group and oral estrogen in the risk of venous thromboembolism among postmenopausal women: The ESTHER study - Marianne, Canonico; Valérie, Olié; Laure, Carcaillon; Pascale, Tubert-Bitter; Pierre-Yves, Scarabin; the EStrogen and THromboEmbolism Risk (ESTHER) Study Group; on behalf of (Thrombosis and Haemostasis, 2008)