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Article History

Received: 12 December 2017

Accepted: 26 April 2018

First Online: 7 May 2018

Ethics approval and consent to participate

: The study was approved by the ethics committee of the People’s Hospital of Zhengzhou, and written informed consent was obtained from all participants.

: All authors provide consent for publication of this paper.

: The authors declare that they have no competing interests.

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