. 2018 Feb 23;97(8):e9616. doi: 10.1097/MD.0000000000009616
Copyright © 2018 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.
Flow diagram of the study selection in the analysis.