Text and Data Mining valid from 2018-10-16
Received: 10 January 2018
Accepted: 28 September 2018
First Online: 16 October 2018
Ethics approval and consent to participate
: Ethical approval for the study was obtained from the ethics committee of Peking University People’s Hospital (Beijing, China). No consent forms were needed because this was a retrospective study.
: Not applicable.
: The authors declare that they have no competing interests.
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