Funding for this research was provided by:
National Natural Science Foundation of China (81470368, 81670187)
Beijing Natural Science Foundation (7172047)
Capital’s Funds for Health Improvement and Research (2018-1-2151)
Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding Support (DFL20151001)
Beijing Medical and Health Foundation (2221-16-157)
Received: 24 October 2018
Accepted: 27 November 2018
First Online: 3 December 2018
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: All procedures performed in studies involving human participants 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. For this type of study formal consent is not required.
: Informed consent was obtained from all individual participants included in the study.