1. Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
2. Department of Medical Statistics, College of Medicine, The Catholic University of Korea, Seoul, Korea.
3. Department of Obstetrics and Gynecology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
4. Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.