Funding for this research was provided by:
National Natural Science Foundation of China (81701953)
Text and Data Mining valid from 2019-12-27
Received: 11 September 2018
Accepted: 16 December 2019
First Online: 27 December 2019
Compliance with ethical standards
: The authors declare no competing interests.
: This was a retrospective study. No patient consent was required. The study was conducted in accordance with the amended Declaration of Helsinki.
: Not applicable.
: All procedures performed in studies involving human participants 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. This article does not contain any studies with animals performed by any of the authors.
: Informed consent was obtained from all individual participants included in the study.