Received: 22 January 2018
Accepted: 2 May 2018
First Online: 11 May 2018
Ethics approval and consent to participate
: This study was approved by the Medical Ethical Committee of National Hospital Organization Tochigi Medical Center (No. 29–10) and was conducted in accordance with the Declaration of Helsinki. This study was also conducted in accordance with the Ethical Guidelines for Epidemiological Research in Japan. The need for individual informed consent was formally waived by the Medical Ethical Committee of National Hospital Organization Tochigi Medical Center because the data were collected from medical records and the patients were not contacted. However, per the Japanese Ethical Guidelines, we displayed a poster in the waiting room of the hospital that provided information on the collection and use of data for this study and the protection of personal information.
: The authors declare that they have no competing interests.
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