Received: 28 December 2018
Accepted: 19 August 2019
First Online: 27 August 2019
Ethics approval and consent to participate
: Due to the retrospective nature of this study, ethics approval by Institutional Review Board of Sun Yat-sen University First Affiliated Hospital was obtained (No. 2016077) and the data were used confidentially for research work. Informed consent was written by every patient when they referred to hospital.
: Not applicable.
: The authors declare that they have no competing interests.