1. Intensive Care Unit, The First Affiliated Hospital of Jinan University, Guangzhou 510630, Guangdong Province, China
2. School of Public Health, Xi’an Jiaotong University Health Science Center, Xian 710061, Shaanxi, China
3. School of Public Health, Shaanxi University of Chinese Medicine, Xianyang 712046, Shaanxi, China
4. Department of Public Health, University of California, Irvine 92697, California, USA