. 2019 Dec 27;98(52):e18313. doi: 10.1097/MD.0000000000018313
Copyright © 2019 the Author(s). Published by Wolters Kluwer Health, Inc.
This is an open access article distributed under the Creative Commons Attribution License 4.0 (CCBY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. http://creativecommons.org/licenses/by/4.0
Figure 1.
Flowchart for study selection in the meta-analysis.