Received: 23 August 2018
Accepted: 21 November 2018
First Online: 6 December 2018
Ethics approval and consent to participate
: This study was reviewed and approved by the institutional Review Board of the First Affiliated Hospital of Nanjing Medical University. The need for patient consent was waived by the same ethics committee.
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.