Funding for this research was provided by:
National Natural Science Foundation of China (81572430 and 81872047)
Text and Data Mining valid from 2019-07-02
Received: 23 March 2018
Accepted: 24 June 2019
First Online: 2 July 2019
Ethics approval and consent to participate
: Not applicable. Because our study is a systematic meta-analysis, the ethics approval and consent to participate is not relevant to our article type.
: Not applicable. There are no details on individuals reported within the manuscript, so we don’t have the consent for publication.
: The authors declare that they have no competing interests.