Text and Data Mining valid from 2018-07-11
Received: 13 February 2018
Accepted: 4 July 2018
First Online: 11 July 2018
Ethics approval and consent to participate
: Ethical approval for the study was granted by the Medical Ethics Committee of Beijing Chao-Yang Hospital (ethics approval number: 2016-K-82). All participants gave informed written consent prior to any collection of data.
: Not applicable.
: The authors declare that they have no competing interests.
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