1. Department of Pulmonary and Critical Care Medicine, The Second Xiangya Hospital, Central South University, Changsha 410011, China
2. Hunan Centre for Evidence-Based Medicine, Changsha 410011, China
3. Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha 410078, China
4. Maternal and Children Health Hospital of Changsha County, Changsha 410100, China
5. Department of Nutrition Science and Food Hygiene, Xiangya School of Public Health, Central South University, Changsha 410078, China
6. Hunan Provincial Key Laboratory of Clinical Epidemiology, Changsha 410078, China