Text and Data Mining valid from 2019-03-30
Received: 30 November 2018
Accepted: 25 March 2019
First Online: 30 March 2019
Compliance with ethical standards
: The authors declare no conflict of interest.
: This study was approved by the local Ethics Committee at Hokkaido University Hospital (Sapporo, Japan; 017-0032). All procedures performed in the present study were in accordance with 1964 Helsinki Declaration and its later amendments.