Received: 14 September 2018
Accepted: 13 May 2019
First Online: 28 May 2019
Ethics approval and consent to participate
: Before the study began, we had carefully consulted the Ethics Committee and Institutional Review Board of West China Hospital. They suggested that this study did not involve special interventions for patients and we should conduct this study in compliance with the Helsinki Declaration and Inform patients fully of the purpose of the study. So, all data was fully anonymised at-source with researchers having access to fully anonymised data only. Given the anonymous nature of the data, the ethics committee waived any requirement for patient informed consent. Nevertheless, patients were informed of the purpose of the study at the start of the study, and all patients were willing to participate in the study and agreed verbally.
: Not applicable.
: The authors declare that they have no competing interests.
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