RA cases validation
In the French prospective general population cohort (E3N). Among the 98,995 included women, we identified and validated self-reported RA cases 3 methods including a specific validation questionnaire, a medical chart review (where available) and the use of the reimbursement database. Among the 3,192 identified potential cases, 964 RA cases were validated, including 698 incident cases and 266 prevalent cases. Of them, 314 (32.6%) were seropositive cases, 23 (2.4%) seronegative and 627 (65.0%) had unknown antibody status. Mean age at diagnosis was 57.4 ± 13.9 years (40.9 ± 10.4 years for prevalent cases, and 63.8 ± 9.0 for incident cases).
Chronic Diarrhoea and Risk of Rheumatoid Arthritis
In the E3N cohort, we assessed the relationship between gastrointestinal disorders and the risk of further development of RA. We observed that chronic diarrhea was associated with an increased risk of subsequent RA development (HR 1.70, 95% CI: 1.13–2.58), particularly among ever-smokers (HR 2.21, 95% CI: 1.32–3.70), independently of dysthyroidism or dietary habits. These data fit with the mucosal origin hypothesis of RA, where interaction between intestinal dysbiosis and smoking could occur at an early stage to promote emergence of autoimmunity, followed years later by clinical disease.
Adherence to the Mediterranean diet and risk of RA
In the E3N cohort, we assessed the relationship between adherence to the Mediterranean diet and risk of RA. We observed that, among ever-smokers, MD score was associated with a decreased risk of RA (HR for 1-point increase of MD score: 0.91; 95% CI: 0.84 to 0.99, P = 0.03).
Hormonal exposure and risk of RA
In the E3N cohort, we assessed the relationships between hormonal exposures and the risk of RA in women. We observed that Early age at menopause (<45 yrs) was associated with an increased risk of RA, particularily in women exposed to tobacco. By contrast, exogenous hormonal exposures were not.