Text and Data Mining valid from 2019-04-27
Received: 25 January 2019
Accepted: 15 April 2019
First Online: 27 April 2019
Ethics approval and consent to participate
: The study protocol was approved by the Ethical Committee of Shandong Provincial Hospital Affiliated to Shandong University (Approval No. 2018–215), which was in accordance with the ethical principles of the Declaration of Helsinki. We obtained written and informed consent from all participants before commencement of the test.
: Not applicable.
: The authors declare that they have no competing interests.
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