Funding for this research was provided by:
the Science and Technology Bureau of Xiangcheng District in Suzhou (no. XJ201706)
Text and Data Mining valid from 2020-02-18
Received: 18 December 2019
Accepted: 14 February 2020
First Online: 18 February 2020
Ethics approval and consent to participate
: The study adhered to the Declaration of Helsinki and ethics approval was obtained from the Institutional Review Board of the Soochow University. Written inform consent was obtained from each participant at the recruitment stage of the study.
: Not applicable.
: The authors declare that they have no competing interests.