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Article History

Received: 4 February 2019

Revised: 25 August 2019

Accepted: 29 September 2019

First Online: 23 October 2019

Compliance with ethical standards

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: The authors declare that they have no conflict of interest.

: This retrospective observational study was approved by the Institutional Review Board (IRB) of Aichi Medical University Hospital (application number 2016-H238) and adhered to the tenets of the Declaration of Helsinki and its amendments. The IRB granted a waiver of informed consent for this study on the basis of the ethical guidelines for medical and health research involving human subjects established by the Japanese Ministry of Education, Culture, Sports, Science, and Technology and the Ministry of Health, Labour, and Welfare. The waiver was granted because the study was a retrospective chart review, not an interventional study, and because it was difficult to obtain consent from patients who had been treated several years prior to the study. Nevertheless, at the request of the IRB, we published an outline of the study, which is available for public viewing on the Aichi Medical University Hospital website. This public posting also gave patients the opportunity to decline participation, although none of the patients did so. Personal identifiers were removed from all records prior to data analysis.