. 2020 Aug 16;12(8):241–255. doi: 10.4253/wjge.v12.i8.241
©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial.
Figure 2.
Overall risk of bias.