Funding for this research was provided by:
Lanzhou Innovation and Entrepreneurship Project (2015-RC-18)
Received: 29 September 2018
Accepted: 11 July 2019
First Online: 26 July 2019
Ethics approval and consent to participate
: This study was conducted in accordance with the declaration of Helsinki. This study was approved by the Ethics Committee of Lanzhou First People’s Hospital. Written informed consent was obtained from all participants.
: Not applicable.
: The authors declare that they have no competing interests.