Text and Data Mining valid from 2019-04-04
Received: 8 February 2019
Accepted: 8 March 2019
First Online: 4 April 2019
Ethics approval and consent to participate
: Written informed consent was obtained from all participants. This study was approved by the ethics committee of Gunma University Graduate School of Medicine (Approval number 13–36).
: Not applicable.
: The authors declare that they have no competing interests.
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