Funding for this research was provided by:
Young Teacher Foundation of Sun Yat-sen University (18ykpy02)
Sun Yat-sen University (2010012)
Text and Data Mining valid from 2019-09-23
Received: 25 July 2019
Accepted: 13 September 2019
First Online: 23 September 2019
Ethics approval and consent to participate
: This is a retrospective trial from public datasets with minimal risk and we petition for waiver of ethics consent.
: We have obtained consents to publish this paper from all the participants of this study.
: The authors declare that they have no competing interests.