Contribution to Authorship:
MP, JZ and WZ conceived the idea of this study.
MP, JZ, WZ and YL designed the search strategy, screened abstracts and
full texts.
YL, DY, LL and XX acquired the data.
JZ and WZ performed the data analysis.
All authors interpreted the data analysis and critically revised the
manuscript.
All authors had the opportunity to review the manuscript, and provided
their permission to publish the manuscript.
All authors agree to take responsibility for the work. The corresponding
author attests that all listed authors meet authorship criteria, and
that no others meeting the criteria have been omitted.