Corresponding Author

Professor

Department of Epidemiology and Statistics, Graduate School, Chinese PLA General Hospital, Beijing, China

Correspondence

Hongying Pi, Department of Nursing, Chinese PLA General Hospital, No. 28 Fuxing Road, Haidian District, Beijing 100853, China.

Email: pihongying@301hospital.com.cn

Xiaoyong Sai, Department of Epidemiology and Statistics, Graduate School, Chinese PLA General Hospital, 28 Fuxing Road, Haidian District, Beijing 100853, China.

Email: saixiaoyong@163.com