Ethics approval and consent to participate

All participating registries obtained the necessary approvals (including written informed patient consent if needed) in accordance with legal, compliance and regulatory requirements from national Data Protection Agencies and/or Research Ethics Boards prior to the data transfer. The study was performed in accordance with the Declaration of Helsinki.

Consent for publication

Not applicable.

Competing interests

Louise Linde, Lykke M. Ørnbjerg and Simon H. Rasmussen: Research grants from Novartis; Thorvardur Jon Love: None; Anne Gitte Loft: Research Grant from Novartis, and speaking and/or consulting fees from AbbVie, Janssen, Lilly, MSD, Novartis, Pfizer, Roche, and UCB; Jakub Zavada: Speaker and consulting fees from Abbvie, Elli-Lilly, Sandoz, Novartis, Egis, UCB; Jiří Vencovský: Consulting and/or speaking fees from Abbvie, Biogen, Boehringer Ingelheim, Eli Lilly, Gilead, Merck Sharp and Dohme, Pfizer and UCB; Karin Laas: Consulting and/or speaking fees from Amgen, Johnson and Johnson and Novartis; Dan C. Nordstrom: Consulting and/or speaking fees from Abbvie, BMS, Lilly, MSD, Novartis, Pfizer, Roche and UCB; Tuulikki Sokka-Isler: non-financial support from DiaGraphIT, personal fees from Abbvie, BMS, Celgene, Medac, Merck, Novartis, Orion Pharma, Pfizer, Roche, Sandoz, UCB and Bohringer Ingelheim, grants from Amgen, outside the submitted work; Bjorn Gudbjornsson: Consulting and/or Speaking fees from Novartis and Nordic-Pharma; Gerdur Gröndal: None, Florenzo Iannone: Consulting and/or speaking from Abbvie, Amgen, AstraZeneca, BMS, Galapagos, Janssen, Lilly, MSD, Novartis, Pfizer, Roche, UCB; Roberta Ramonda:  Consulting and/or speaking fees from AbbVie, Eli Lilly, Janssens, Novartis, UCB and Pfizer; Pasoon Hellamand: Research grant from Novartis; Eirik K. Kristianslund: None; Tore K. Kvien: Fees for speaking and/or consulting last 2 years from AbbVie, Amgen, Celltrion, Gilead, Grünenthal, Novartis, Pfizer, Sandoz, UCB and research funding to Diakonhjemmet Hospital from AbbVie, BMS, Galapagos, Novartis, Pfizer and UCB; Ana M. Rodrigues: Research grant from Novartis, Pfizer, Amgen, consulting and/or speaking from Abbvie, Amgen; Maria J. Santos: Speaker fees from Abbvie, AstraZeneca, Lilly, Novartis and Pfizer; Catalin Codreanu: Speaker and consultancy fees from AbbVie, Amgen, Boehringer Ingelheim, Ewopharma, Lilly, Novartis, Pfizer; Ziga Rotar: Speaker or consultancy fees from Abbvie, Novartis, MSD, Medis, Biogen, Eli Lilly, Pfizer, Sanofi, Lek, Janssen; Matija Tomšič: Consulting and/or speaking fees from Abbvie, Amgen, Biogen, Eli Lilly, Janssen, Medis, MSD, Novartis, Pfizer, Sanofi, Sandoz-Lek; Isabel Castrejon: Speaker and/or consultancy fees from BMS, Eli-Lilly, Galapagos, Gilead, Janssen, Novartis, MSD, Pfizer, GSK; Federico Díaz-Gonzáles: None; Daniela Di Giuseppe: None; Lotta Ljung: No grants, consulting or speaking fees, but has, for Karolinska University Hospital and as register holder for the Swedish Rheumatology Register in the last years agreements with Abbvie, Amgen, Eli Lilly, Galapagos, Novartis, Pfizer, Sanofi, Sobi, UCB, Janssen, BMS, GSK, Otsuka; Michael J. Nissen: Consulting and/or speaking fees from AbbVie, Eli Lilly, Janssens, Novartis and Pfizer; Adrian Ciurea: Consulting and/or speaking fees from AbbVie, Eli Lilly, Merck Sharp & Dohme, Novartis, Pfizer; Gary J. Macfarlane: Research grant from GSK; Maureen Heddle: None; Bente Glintborg: Research grants from Pfizer, AbbVie, BMS, Sandoz; Mikkel Østergaard: Research grants from Abbvie, BMS, Merck, Celgene and Novartis, and speaker and/or consultancy fees from Abbvie, BMS, Boehringer-Ingelheim, Celgene, Eli-Lilly, Hospira, Janssen, Merck, Novartis, Novo, Orion, Pfizer, Regeneron, Roche, Sandoz, Sanofi and UCB; Merete L. Hetland: Research grants from Abbvie, Biogen, BMS, Celltrion, Eli Lilly, Janssen Biologics B.V, Lundbeck Fonden, MSD, Medac, Pfizer, Roche, Samsung Biopies, Sandoz, Novartis