Text and Data Mining valid from 2019-08-28
Received: 12 June 2019
Accepted: 19 August 2019
First Online: 28 August 2019
Ethics approval and consent to participate
: This study was approved by the Ethics Committee of Kyushu University (Approval No. 277). All subjects of this study gave their written informed consent to participate in this study.
: Not applicable.
: The authors declare that they have no competing interests.