Funding for this research was provided by:
Jining Medical University Helin Academician Fund (JYHL2018FMS13)
Supporting Fund for Teachers' Research at Jining Medical University (JYFC2018FKJ048)
Jining Science and Technology Bureau Medical Health Fund (2018SMNS002)
Text and Data Mining valid from 2020-03-17
Received: 25 November 2019
Accepted: 21 February 2020
First Online: 17 March 2020
Ethics approval and consent to participate
: This retrospective study was approved by the relevant Institutional Review Board at the Affiliated Hospital of Jining Medical University. The reference number is not applicable. Explicit informed consent for this retrospective study was not required.
: Not applicable.
: The authors declare that they have no competing interests.