Text and Data Mining valid from 2018-07-11
Received: 19 February 2018
Accepted: 26 June 2018
First Online: 11 July 2018
Ethics approval and consent to participate
: This is a cross-sectional study conducted at the Peking University People’s Hospital (PUPH) from Oct 2015 to Feb 2017 and approved by the PUPH ethics committee (2014PHB098–01). All volunteers were informed and signed the consent form.
: Not applicable
: The authors declare that they have no competing interests.
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