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Article History

Received: 25 October 2018

Accepted: 30 April 2019

First Online: 22 May 2019

Ethics approval and consent to participate

: Our study was approved by the medical ethics committee of the Peking Union Medical College, registration number: S-K438. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

: Based on the Declaration of Helsinki, verbal informed consent was obtained from all patients included in the trial, parental consent was obtained for participants below 18 years old. The ethics committee approved this procedure. This article does not contain any studies with animals performed by any of the authors.

: The authors declare that they have no conflicts of interest.

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