Acknowledgements
We would like to thank Editage (www.editage.jp) for assistance with editing this manuscript.
Disclosure statement
No potential conflict of interest was reported by the authors.
Author’s contributions
All authors meet the ICMJE authorship criteria. HH was responsible for the study design and data analyses. HY, SK, YI, and NH contributed to the data interpretation. All authors critically revised the report, commented on drafts of the manuscript, and approved the final report.