1. Department of Internal Medicine, SoonChunHyang University School of Medicine, Bucheon 14584, Republic of Korea
2. Department of Medicine, Chung-Ang University Gwangmyeong Hospital, Gwangmyeong 06973, Republic of Korea
3. Department of Statistics, SoonChunHyang University School of Medicine, Bucheon 31538, Republic of Korea
4. Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Republic of Korea