Funding for this research was provided by:
Health and Family Planning Commission of Sichuan Province (20164Y0130)
Text and Data Mining valid from 2019-02-18
Received: 29 October 2018
Accepted: 7 January 2019
First Online: 18 February 2019
Ethics approval and consent to participate
: All the participants’ guardian informed consents were obtained. The present study was approved by the independent ethics committee of Shanghai Ninth People’s Hospital affiliated with Shanghai Jiao Tong University, School of Medicine (IRB number: 201592).
: 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.