Received: 5 January 2019
Accepted: 13 May 2019
First Online: 24 May 2019
Ethics approval and consent to participate
: The Ethics committee of the Guangdong Provincial People’s Hospital, as well as the committees of Xiaolan Hospital of Southern Medical University and Guangzhou Nansha Central Hospital, approved the protocol. Written informed consent was obtained from each patient or from appropriate guardian.
: Not applicable. No individual personal data are included in the study. All patients provided necessary consent to participate in the present study.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.