Funding for this research was provided by:
the Yangfan Project Special Foundation of Beijing Hospital Authority (ZXLY201606)
Received: 20 March 2019
Accepted: 30 August 2019
First Online: 16 October 2019
Ethics approval and consent to participate
: The study was approved by the Ethics Committee of the Chao-Yang Hospital, Beijing. All participants provided written informed consent.
: Not applicable.
: The authors declare that they have no competing interests.