Footnotes

• Handling editor Josef S Smolen

• Contributors CT conceived the study design. HT and CT analysed the data. HT and CT wrote the main manuscript text. KY, KI, MH, MF, HI, TF, KO, AT, HY and TM contributed to collection of samples and/or data. KY and MF counted SHS score for the IORRA and KURAMA, respectively. WY aggregated the KURAMA database. All authors reviewed the manuscript.

• Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

• Competing interests None declared.

• Patient consent Obtained.

• Ethics approval Kyoto University Graduate School of Medicine.

• Provenance and peer review Not commissioned; externally peer reviewed.