Text and Data Mining valid from 2020-02-07
Received: 21 October 2019
Accepted: 15 January 2020
First Online: 7 February 2020
Compliance with ethical standards
: The study was approved by the ethics committee of Beijing Chaoyang Hospital and performed in accordance with the Declaration of Helsinki. All subjects provided written informed consent.
: The authors declare that they have no conflict of interest.