Funding for this research was provided by:
Beijing Municipal Science & Technology Commission (Z161100000516147)
National Natural Science Foundation of China (81372737)
Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding Support (ZYLX201604)
Received: 31 August 2018
Accepted: 26 June 2019
First Online: 19 July 2019
Ethics approval and consent to participate
: This study was approved by the ethics committee of Beijing Friendship Hospital and was performed in accordance with the ethical guidelines of the 1964 Declaration of Helsinki and its later amendments. The written informed consent was obtained from all participants.
: Not applicable.
: The authors declare that they have no competing interests.