Article History
Received: 26 August 2019
Accepted: 12 September 2019
First Online: 3 November 2019
Compliance with ethical standards
: All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The Institutional Review Board of Linqing People’s Hospital approved this study.
: The authors declare that they have no conflict of interest.