Funding for this research was provided by:
Science and Technology Planning Project of Guangdong Province (2017A020215160)
Shenzhen Municipal Government (KQTD2016112809330877)
Received: 15 November 2018
Revised: 18 February 2019
Accepted: 14 March 2019
First Online: 30 April 2019
Compliance with ethical standards
: The scientific guarantor of this publication is Dr. Jun Xia.
: The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.
: No complex statistical methods were necessary for this paper.
: Written informed consent was not required for this study because this was a retrospective study.
: Institutional Review Board approval was obtained.
: • retrospective• diagnostic or prognostic study• multicenter study