Received: 3 July 2018
Accepted: 3 September 2018
First Online: 10 September 2018
Ethics approval and consent to participate
: Approval for this retrospective study (approval no. 2017-013) was provided by the Ethical Committee of Kumamoto Central Hospital, Kumamoto, Japan, on December 27, 2017.
: All data were pre-existing data obtained from the patient’s medical records and did not include any personal information that would identify any of the patients. Informed consent from the patients was therefore waived, based on the Ethical Guidelines for Epidemiological Studies issued jointly by the Ministry of Health, Labour and Welfare and the Ministry of Education, Culture, Sports, Science, and Technology of Japan.
: The author declares that he has no competing interests.
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