Received: 24 February 2018
Accepted: 31 May 2018
First Online: 8 June 2018
Ethics approval and consent to participate
: This study was conducted under compliance with the Declaration of Helsinki and were approved by the Human Ethics Committee of Jining NO.1 People’s Hospital and the Human Ethics Committee of Qingdao NO.6 People’s Hospital.
: All the authors declared that there is no conflicts of interests.
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