1. From the Department of Preventive Medicine (J.S.), Kangwon National University College of Medicine, Chunchon, Korea; the Department of Family Medicine (Y.-M.S.) and Center for Health Promotion (Y.-H.C.), Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea; the Department of Epidemiology and Population Health (S.E.), London School of Hygiene and Tropical Medicine, London, England; and the Department of Social Medicine (G.D.S.), University of Bristol, Bristol, England.