Funding for this research was provided by:
Capital’s Funds for Health Improvement and Research (2018-2-2095)
Text and Data Mining valid from 2019-11-04
Received: 11 March 2019
Accepted: 16 October 2019
First Online: 4 November 2019
Ethics approval and consent to participate
: This study was approved by the Beijing Children’s Hospital Institutional Ethics Committee. Informed consents were obtained from the parents or their guardians in accordance with the Declaration of Helsinki.
: Not applicable.
: The authors declare that they have no competing interests.