Department of Family Medicine, Hallym University Sacred Heart Hospital, Anyang, Gyeonggi-do, Republic of Korea. Biocenter Oulu, Research Unit of Internal Medicine, University of Oulu, Oulu, Finland. Research Center of Internal Medicine, Oulu University Hospital, Oulu, Finland. Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland. Unit of Medicine, Oulu University Hospital, Oulu, Finland. Oulu Advanced Research on Service and Information Systems, Faculty of Information Technology and Electrical Engineering, University of Oulu, Oulu, Finland. Department of Statistics, Hallym University, Chuncheon, Gangwon-do, Republic of Korea.