Table 1.

Summary of questionnaire content for participants, SCREEN-RA cohort, Switzerland, 2009–2020

Questionnaire component	Summary of content
General information	Contact information, age, gender, ethnicity, country of origin, birth weight, years of education
Physical examination	Absence of systemic inflammatory disease, height, weight, blood pressure, number of swollen joints, no of tender joints, presence of rheumatoid nodules.
Family information	Family’s country of origin, number of relatives with RA or other autoimmune conditions, number of siblings, no of children, relation to the RA-diagnosed relative, age of beginning of symptoms, age of diagnosis, anti-CCP testing, medication of the RA-relative.
Annual follow-up questionnaire	Joint pain assessment, joint swelling assessment, recent blood test for RA for Lupus, current health issues, current medication, history of infectious disease, history of female hormonal factors, vaccinal status, smoking status, consumption of tea/coffee/soft-drinks, use of vitamin supplementation, alcohol consumption, professional situation, sleeping disorders, physical activity.
Annual follow-up questionnaire (optional)	Dust exposition at workplace, professional health, oral health, consumption of seafoods.
In case of stool sample (optional)	Time since last defecation, stool consistency, recent travel, use of probiotics, use of antibiotics, recent surgery, current periodontitis. A Food Frequency Questionnaire.
In case of oral sample (optional)	Allergies, current medication, smoking status, number of teeth, reason for tooth loss, no of implants, oral hygiene habits, chewing problems, breath problems, periodontal status.

CCP, cyclic citrullinated peptide; RA, rheumatoid arthritis; SCREEN-RA, Evaluation of a SCREENing strategy for Rheumatoid Arthritis.