1. Department of Epidemiology, Ningxia Medical University, Yinchuan, People’s Republic of China
2. Suicide Research and Prevention Center, Shanghai Mental Health Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
3. School of Medicine, Duke University Medical Center, Durham, NC, USA
4. Departments of Psychiatry and Epidemiology, Columbia University, New York, NY, USA