Text and Data Mining valid from 2019-04-04
Received: 25 October 2018
Accepted: 27 March 2019
First Online: 4 April 2019
Ethics approval and consent to participate
: All procedures were performed in accordance with Helsinki declaration. This study was approved by the ethics committee of Niigata University on August 2nd, 2018 and is known under reference number 2018–0133. Written informed consents were obtained from all patients before surgery. In this study, the requirement for informed consent was waived because this was a retrospective study according to the Ethical Guidelines for Medical and Health Research Involving Human Subjects of Ministry of Health, Labour and Welfare of Japan. All participants were provided opportunities to decline participation in the study prior to the present investigation.
: Not applicable.
: The authors declare that they have no competing interests.
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