1. School of Nursing, Nanjing Medical University, Nanjing 210029, China
2. The Nethersole School of Nursing, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong 999077, China
3. School of Public Health, National Heart and Lung Institute, Imperial College London, London W12 7RQ, UK
4. School of Nursing, Lanzhou University, Lanzhou 730000, China