1. Clinical Trial Service Unit and Epidemiological Studies Unit, Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom
2. Medical Research Council Population Health Research Unit, Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom
3. Chinese Academy of Medical Sciences, Beijing, China
4. Department of Epidemiology and Biostatistics, School of Public Health, Peking University Health Science Center, Beijing, China