Text and Data Mining valid from 2019-11-21
Received: 16 March 2019
Accepted: 11 November 2019
First Online: 21 November 2019
Ethics approval and consent to participate
: The study was reviewed and approved by the Medical Ethics Committee of Qingdao No.6 People’s Hospital. Since all specimens used were anonymous, the Medical Ethics Committee exempted patients from the need for informed consent.
: Not applicable.
: The authors declare that they have no competing interests.