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First Online: 12 September 2020

Declarations

:

: No external funding was used in the preparation of this manuscript.

: Hong-yu Kuang, Qiang Li, Hua-an Du, Min Chen, and Yue-hui Yin declare they have no potential conflicts of interest that might be relevant to the contents of this manuscript.

: Ethical approval was waived because each study has been previously published.

: All co-authors have consented the participation in this work.

: All co-authors have consented for publication of this study.

: :The relevant data and materials can be requested from the authors.

: The codes for meta-analyses with the statistical software Stata 14.1 can be requested from the authors.