Funding for this research was provided by:
China Medical Board (16-259)
Received: 3 September 2018
Accepted: 4 January 2019
First Online: 18 January 2019
Ethics approval and consent to participate
: Our study was approved by Peking University Institutional Review Board (IRB number: IRB00001052–18005). No patients were involved in developing outcome measures and no analyses included any identifiable patient data.
: Not applicable.
: The authors declare that they have no competing interests.
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