Text and Data Mining valid from 2019-01-12
Received: 18 October 2018
Accepted: 11 December 2018
First Online: 12 January 2019
Ethics approval and consent to participate
: This study was conducted in accordance with the Declaration of Helsinki and had been approved by the West China Hospital Clinical Trials and Biomedical Ethics Committee, Sichuan University (Approved in 2012, No. 265). No informed consent was available due to the retrospective design.
: Not applicable.
: The authors declare that they have no competing interests.
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