Article History
Received: 22 January 2018
Accepted: 28 May 2018
First Online: 14 June 2018
Ethics approval and consent to participate
: The study was approved by the Medical Ethics Committee of the Fourth Hospital of Hebei Medical University in China on September 30, 2013. The approval letter # was documented as the file named as “C-20130930” in Chinese.
: The authors declare that they have no competing interests.
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