Funding for this research was provided by:
China Medical Board (10-029)
Received: 15 November 2016
Accepted: 20 April 2018
First Online: 2 May 2018
Ethics approval and consent to participate
: This study was approved by the Ethics Committee of School of Medicine of Xi’an Jiaotong University (China), and the approval number was 2,014,189. The researchers received verbal consent from the participants for participation in this study through pre-telephone interviews.
: The authors declare that they have no competing interests.
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