Received: 11 June 2018
Accepted: 16 May 2019
First Online: 23 May 2019
Ethics approval and consent to participate
: The study was approved by the Medical Ethics Committee of Beijing Youan Hospital, Capital Medical University, China. As the analysis used anonymous clinical data, the patients were not required to give informed consent for the study.
: Not applicable.
: The authors declare that they have no competing interests.
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