Ethics approval and consent to participate
The study was approved by the Regional Ethical Review Board for southern Sweden (2013/192 and 2015/62) and the National Ethical Review Agency (2020-02935).
Consent for publication
Not applicable.
Availability of data and material
The datasets generated and analyzed during this current study are not publicly available as they contain information that could compromise research participant privacy. The data are available and anonymized from the corresponding author (EB) on reasonable request and appropriate permission from regulatory authorities.
Competing interests
The authors declare that they have no competing interests.
Funding
This study was supported by grants from the Swedish Rheumatism Association, Greta and Johan Kock’s Foundation, the Anna-Greta Crafoord Foundation, the Crafoord Foundation, the Swedish Medical Society, Alfred Österlunds Foundation, Magnus Bergvall Foundation, Thelma Zoega’s foundation, King Gustaf V's 80-year foundation, Lions research fund Skåne, The Knut and Alice Wallenberg foundation, the Medical Faculty at Lund University and Region Skåne (all to RK). The funders had no role in the concept, design, or interpretation of data.
Author’s contributions
EB conceptualized the study, acquired, analyzed and interpreted the data and wrote the manuscript. AD and HT assisted in analysis and interpretation of data. BM was one of the initiators in forming the cohort and assisted in the interpretation of the results. RK conceptualized the study and interpreted data. All authors have reviewed and revised the manuscript.
Acknowledgements
The authors wish to thank Minna Willim for the help in managing the data in the cohort, Jenny Sandgren at Clinical Studies - Forum south, Sweden for advice on choice of statistical method and Anna Jöud for the valuable discussions on statistical analysis. We also thank Tore Saxne for his advice in forming the cohort. Finally, we are grateful to Pierre Geborek for initiating the idea of a cohort of all JIA children at Skåne University Hospital.