Received: 2 April 2021
Accepted: 21 July 2021
First Online: 13 August 2021
: Ethics approval has been granted by the Research Ethics Committee of Beijing Children’s Hospital (2018-96). All the data were collected retrospectively and anonymized in a standardized case report form in the hospital database. All participants were provided with written information about the study. Written informed consent of all study participants from their parents/guardians were obtained and documented in accordance with the Institutional policy.
: Not applicable.
: The authors declare no competing interests.