Text and Data Mining valid from 2019-04-09
Received: 6 September 2018
Accepted: 21 March 2019
First Online: 9 April 2019
Ethics approval and consent to participate
: The study protocol was approved by the Peking University Medical Ethics Committee (IRB00001052–14058). All participants provided written informed consent.
: Not applicable.
: The authors declare that they have no competing interests.
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