Funding for this research was provided by:
Capital’s Funds for Health Improvement and Research (2018-2-2095)
Received: 19 August 2019
Accepted: 20 January 2020
First Online: 6 February 2020
Ethics approval and consent to participate
: This research was approved by the Beijing Children’s Hospital Institutional Ethics Committee (No. 2016–65) and was conducted in accordance with the principles of the Declaration of Helsinki. The parents or guardians of all patients provided written informed consent.
: Not applicable.
: The authors declare that they have no competing interests.