Funding for this research was provided by:
the Natural Science Foundation of Hubei Province (2012FFB05501, 2011CDC124)
Wuhan Municipal Public Health Bureau (WG12D01)
Wuhan Municipal Human Resources and Social Security Bureau
Text and Data Mining valid from 2018-09-18
Received: 18 October 2017
Accepted: 6 September 2018
First Online: 18 September 2018
Compliance with ethical standards
: The authors declare that they have no conflicts of interest.
: All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Informed consent was obtained from all individual participants included in the study.