1. Department of Epidemiology and Biostatistics, West China School of Public Health; Sichuan University; Chengdu China
2. Department of Pathophysiology, West China School of Basic and Forensic Medicine; Sichuan University; Chengdu China
3. Division of Population Medicine; Cardiff University; Cardiff UK
4. Department of Biostatistics and Health Informatics, Institute of Psychiatry, Psychology & Neuroscience; King's College London; London UK
5. Cochrane Skin Group, School of Medicine; Nottingham University; Nottingham UK