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Article History

Received: 29 May 2018

Accepted: 26 November 2018

First Online: 5 December 2018

Ethics approval and consent to participate

: The Institutional Review Board of Peking Union Medical College Hospital approved this study and written informed consent was obtained from the participants.

: Not applicable.

: The authors declared that they had no competing interests.

: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.