Characteristics of the Swedish, Danish and Norwegian data collections used to derive the analytical RA treatment cohorts
| Country | Sweden | Denmark | Norway | ||||||
| Source cohort | EIRA | SRQ | SRQ biobank | DANBIO | DRB* | NOR-DMARD | ULRABIT | ARCTIC | NOR-VEAC |
| Years of operation | 1996 and onwards | 1995 and onwards | 2012 and onwards | 2000 and onwards | 2015 and onwards | 2000 and onwards | 2010–2013 | 2010–2015 | 2010–2016 |
| Early or Established RA | Early | Early and established | Early and established | Early and established | Early and established | Early and established | Established | Early | Early |
| Coverage | Central and southern parts of Sweden | Nationwide | Some 14 participating centres across the country | Nationwide | 10–12 participating centres across the country | Currently 4 (previously 6) geographically spread hospitals in Norway | From single site | 13 Norwegian Rheumatology clinics | Seven RA clinics in central and southern Norway |
| RA inclusion criteria | Newly diagnosed RA diagnosed by a rheumatologist (EULAR/ACR 2010 or ACR 1987) | Clinical diagnosis of RA by a rheumatologist (EULAR/ACR 2010/ACR 1987) | Inclusion in SRQ, plus: early RA, or starting or having stared a b/tsDMARD during the last 2 years. | Clinical diagnosis of RA by a rheumatologist (EULAR/ACR 2010/ACR 1987) | Inclusion in DANBIO | Clinical diagnosis of RA by a rheumatologist (EULAR/ACR 2010 or ACR 1987) | Clinical diagnosis of RA by a rheumatologist (ACR 1987) | Clinical diagnosis of RA by a rheumatologist (EULAR/ACR 2010 or ACR 1987) | Clinical diagnosis of RA by a rheumatologist (EULAR/ACR 2010 or ACR 1987) |
| Study design | Research project. Incident case–control study with RA as incident cases and population-based controls | Nationwide prospective clinically integrated quality of care register with data entry by the rheumatologist and the patient | Research project. Cohort study. | Nationwide prospective clinically integrated quality of care register with data entry by the rheumatologist and the patient | Research project affiliated to DANBIO | Longitudinal observational study | Longitudinal observational study | Randomised controlled trial | Longitudinal observational study |
| Data capture | Questionnaires and blood samples | Data entered by the rheumatologist and the patient | One-time blood sample | Data entered by the rheumatologist and the patient | Blood sample (one or several per patient) | Data entered by the rheumatologist and the patient, 1–2 blood samples on subset of patients | Data entered by the rheumatologist and the patient, multiple blood samples per patient | Data entered by the rheumatologist and the patient, multiple blood samples per patient | Data entered by the rheumatologist and the patient, multiple blood samples per patient |
*DRB is a subcohort of the DANBIO cohort.
ACR, American Congress of Rheumatology; ARCTIC, Aiming for Remission in rheumatoid arthritis: a randomised trial examining the benefit of ultrasound in a Clinical TIght Control regimen; DANBIO, Danish Registry for Biologic Therapies in Rheumatology; DMARD, disease-modifying antirheumatic drug; DRB, Danish Rheumatologic Biobank; EIRA, Epidemiological Investigation of RA; EULAR, European Alliance of Associations for Rheumatology; NOR-DMARD, The Norwegian Antirheumatic Drug Register; NOR-VEAC, Norwegian Very Early Arthritic Clinic; RA, rheumatoid arthritis; SRQ, Swedish Rheumatology Quality register; ULRABIT, ULtrasound in Rheumatoid Arthritis patients starting BIologic Treatment.