Funding for this research was provided by:
National Natural Science Foundation of China (71673098)
Text and Data Mining valid from 2020-03-30
Received: 2 December 2019
Accepted: 23 March 2020
First Online: 30 March 2020
Ethics approval and consent to participate
: Ethical approval was obtained from the Ethics Committee of Tongji Medical College, Huazhong University of Science & Technology (IORG No: IORG0003571). Permission was taken from the National Health Commission of People’s Republic China and the manager of each hospital.
: Not applicable.
: The authors declare that they have no competing interests.