Footnotes

• Handling editor Josef S Smolen

• Contributors All authors were involved in drafting the letter or revising it critically for important intellectual content and approved the final manuscript to be submitted and agreed to be accountable for all aspects of the work. Conception and design of the ARCTIC study: A-BA, ICO, HBH, TU, DvdH, TKK, SL and EAH. Acquisition of data: A-BA, HBH, TU and EAH. Analysis and interpretation of data: NPS, A-BA, ICO, HBH, TU, DvdH, TK, SL and EAH. EAH and SL are shared last authors.

• Funding The ARCTIC study has received grants from the Norwegian Research Council, the South-East Health Region in Norway, the Norwegian Rheumatism Association, the Norwegian Women’s public Health Association and unrestricted grant support from AbbVie, Pfizer, MSD, Roche and UCB. The funders of the study had no role in study design, data collection, data analysis, data interpretation or writing of the report. The corresponding author had full access to all the data in the study and had final responsibility for the decision to submit for publication.

• Competing interests Dr NPS reports grants from The South-Eastern Norway Regional Health Authority, during the conduct of the study; Dr Aga reports personal fees from Abbvie, personal fees from Eli Lilly, personal fees from Novartis, personal fees from Pfizer, outside the submitted work; Dr ICO has nothing to disclose; Dr NBH reports personal fees from AbbVie, personal fees from Novartis, personal fees from Lilly, outside the submitted work; Dr TU reports personal fees from Lilly, personal fees from Novartis, outside the submitted work; Dr DvdHv reports personal fees from AbbVie, Amgen, Astellas, AstraZeneca, Bayer, BMS, Boehringer Ingelheim, Celgene, Cyxone, Daiichi, Eisai, Galapagos, Gilead, Glaxo-Smith-Kline, Janssen, Lilly, Merck, Novartis, Pfizer, Regeneron, Roche, Sanofi, Takeda, UCB Pharma, outside the submitted work; and Director Imaging Rheumatology BV; Dr TKK reports personal fees from Amgen, personal fees from Celltrion, personal fees from Egis, personal fees from Evapharma, personal fees from Ewopharma, personal fees from Hikma, personal fees from Oktal, personal fees from Sandoz, personal fees from Sanofi, personal fees from Abbvie, personal fees from BMS, personal fees from MSD, personal fees from Pfizer, grants from UCB, personal fees from Biogen, personal fees from Eli Lilly, personal fees from Gilead, personal fees from Mylan, personal fees from Novartis, outside the submitted work; Dr EAH reports grants from The Research Council of Norway, grants from The South-Eastern Norway Regional Health Authority, during the conduct of the study; personal fees from Pfizer, from AbbVie, personal fees from Celgene, personal fees from Novartis, personal fees from Janssen, personal fees from Gilead, personal fees from Eli-Lilly, personal fees from UCB, outside the submitted work; Dr SL reports grants from The South-Eastern Norway Regional Health Authority, grants from The Research Council of Norway, grants from Norwegian Women’s Public Health Association, grants from Norwegian Rheumatism Association, grants from AbbVie, grants from UCB Pharma, grants from Pfizer Inc, grants from MSD Norway, grants from Roche Norway, during the conduct of the study.

• Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

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