Liu, Lu
Hou, Lei
Yu, Yuanyuan
Liu, Xinhui
Sun, Xiaoru
Yang, Fan
Wang, Qing
Jing, Ming
Xu, Yeping
Li, Hongkai
Xue, Fuzhong
Funding for this research was provided by:
National Natural Science Foundation of China (81773547)
Natural Science Foundation of Shandong Province (ZR2019ZD02)
Article History
Received: 7 February 2020
Accepted: 12 June 2020
First Online: 22 July 2020
Ethics approval and consent to participate
: All procedures involving human participants were performed in accordance with the ethical standards of the Ethics Committee of Public Health, Shandong University (No.20190401). Since the study dataset just involved routine available data collection launched by the government, informed consent was not specifically obtained.
: Not applicable.
: The authors declare that they have no competing interests.