The Coronary Computed Tomography Angiography in Rheumatoid Arthritis study is part of the multinational, prospective, observational Autoimmunity and Atherosclerosis in Rheumatic Diseases cohort (https://atacc-rd.com) that includes comprehensive baseline and follow-up assessments at 3, 5, and 10 years. It comprises a main protocol and several optional modules, including a Cardiac Imaging Module, Biobanking Module, Pulmonary Module, and Anxiety and Depression Module.

The study aims to advance understanding of cardiopulmonary and psychological comorbidities in rheumatoid arthritis, to improve early identification and management, and to enhance insights into underlying disease mechanisms-ultimately refining risk stratification and targeted prevention strategies.

The study includes 4,000 patients with rheumatoid arthritis enrolled through the Cardiac Imaging Module in the main protocol. Participants undergo coronary computed tomography angiography, pulmonary function testing, physical examination, questionnaires, and biobanking, supplemented by genetic, proteomic, metabolomic, and microbiome profiling.

This prospective, observational study follows individuals with rheumatoid arthritis over time to understand how the disease and its treatment relate to cardiovascular, pulmonary, psychological, and biological outcomes. The study collects standardized clinical data from outpatient rheumatology clinics, complemented by advanced imaging, biological sample collection, and linkage to national health registries.

Study Procedures and Visit Schedule Participants are enrolled during routine or ad-hoc outpatient visits. After informed consent, a baseline evaluation is performed, followed by standardized follow-up visits after approximately 3, 5, and 10 years (± 3-6 months).

At baseline, demographic and lifestyle factors (age, sex, education, smoking, alcohol, physical activity, and family history) are recorded together with anthropometric measures (height, weight, waist circumference) and rheumatoid arthritis characteristics (serologic status, disease duration, erosive disease, and disease activity scores). Concomitant diseases and medications are documented, and vital signs and blood pressure are measured.

Patient-reported outcomes include validated questionnaires on quality of life (Short Form 36, version 1), functional ability (Multidimensional Health Assessment Questionnaire), work productivity (Work Productivity and Activity Impairment - General Health), fatigue and pain visual analogue scales, physical activity (International Physical Activity Questionnaire - Short Form), and shortness of breath (University of California, San Diego Shortness of Breath Questionnaire). Laboratory results, including markers of inflammation and metabolic status, are obtained according to routine standards.

Follow-up visits repeat these assessments to evaluate disease activity, lifestyle changes, and incident comorbidities. Events such as hospitalizations, procedures, and deaths are continuously updated through registry linkage, ensuring complete longitudinal follow-up.

Registry Data Sources All participants are linked to national Danish health and administrative registries to enable comprehensive, long-term follow-up. The study integrates data from the National Patient Registry, the Danish Rheumatology Quality Database, the Civil Registration System, the Danish National Causes of Death Registry, the Western Denmark Heart Registry, the Danish Heart Registry, the Danish Stroke Registry, the Danish National Vascular Registry, the Danish National Database of Reimbursed Prescriptions, the Clinical Laboratory Information System, the Register of Laboratory Results for Research, and the Danish Research Institute for Economic Analysis and Modelling. Linkage across these registries allows continuous capture of clinical events, treatments, and vital status, ensuring complete longitudinal follow-up and verification of outcomes recorded during study visits.

Governance The study is governed by an executive steering committee responsible for overall scientific direction, study design, resource allocation, and regulatory compliance. Supporting boards and advisory groups contribute to patient involvement, methodological quality, and international collaboration. Dedicated centers coordinate site operations, biobanking, cardiac imaging, and data analysis to ensure standardized procedures and data integrity across all participating sites.

All procedures are conducted in accordance with Danish and European data-protection regulations, and data are stored and managed in secure systems compliant with the General Data Protection Regulation.

Inclusion Criteria:

• Fulfill the ACR/EULAR-2010 criteria for rheumatoid arthritis
• Attending or has attended at least one visit during the last two years in rheumatology outpatient clinic for diagnostic or monitoring purposes related to rheumatoid arthritis
• Age 50-75 years

Exclusion Criteria:

• Diagnosed with overlapping systemic autoimmune diseases other than secondary Sjogren's syndrome
• Active cancer
• Prior coronary atherosclerotic symptoms as defined by myocardial infraction, percutaneous coronary intervention, or coronary artery bypass grafting
• Allergy to radiocontrast agents
• Estimated glomerular filtration rate (eGFR) < 30 mL/min
• BMI > 35 kg/m2
• Persistent atrial fibrillation

Patients with rheumatoid arthritis from rheumatology outpatient clinics across Denmark.

All IPD collected throughout the study.

After completion of the study.

Individuals who obtain approval from the Danish Ethical Review Authority, the authority responsible for personal data, and the COTIRA Steering Committee will be able to access all PIDs as described above.