Received: 7 November 2020
Accepted: 29 January 2021
First Online: 11 February 2021
Ethics approval and consent to participate
: This study adheres to the ethical principles of the Declaration of Helsinki. It was approved by the Ethics Committee of Beijing Children’s Hospital (2020-k-12). For the presented retrospective data, the requirement to obtain informed consent was waived in accordance with the vote of the Ethics Committee.
: Not applicable.
: The authors declare that they have no competing interests.