Xue-Ying Xu, Wu-Sheng Wang, Qi-Meng Zhang, Jun-Ling Li, Jin-Bin Sun, Tian-Tian Qin, Hong-Bo Liu, Department of Epidemiology and Health Statistics, School of Public Health, China Medical University, Shenyang 110122, Liaoning Province, China
Author contributions: Xu XY, Wang WS, Zhang QM, Li JL, and Liu HB designed the research; Xu XY, Zhang QM, Li JL, Sun JB, and Qin TT performed the research; Sun JB and Qin TT contributed new analytic tools; Xu XY, Wang WS, and Zhang QM analyzed the data; Xu XY, Wang WS, Zhang QM, and Liu HB wrote the paper.
Supported by Social Science Foundation of Liaoning Province, No. L18ATJ001.
Conflict-of-interest statement: The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted. All authors declare that they have no conflicts of interest.
PRISMA 2009 Checklist statement: The authors have read the PRISMA 2009 checklist, and the manuscript was prepared and revised according to the PRISMA 2009 checklist.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (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. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Hong-Bo Liu, PhD, Professor, Research Fellow, Research Scientist, Statistician, Department of Epidemiology and Health Statistics, School of Public Health, China Medical University, No. 77, Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning Province, China. firstname.lastname@example.org
Received: March 4, 2019
Peer-review started: March 4, 2019
First decision: May 31, 2019
Revised: June 25, 2019
Accepted: July 3, 2019
Article in press: July 3, 2019
Published online: August 6, 2019