Funding for this research was provided by:
National Nature Science Foundation of China (81273180)
Key Research and Development Project of Shanxi Province (201603D321101)
Received: 22 August 2017
Accepted: 27 February 2018
First Online: 20 March 2018
Ethics approval and consent to participate
: The study protocol received medical and ethical approval from Shanxi Medical University. All participants provided written informed consent and received compensation for their time and effort.
: All authors have approved the manuscript for publication.
: The authors declare that they have no competing interests.
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