Female hormonal factors and the development of anti-citrullinated protein antibodies in women at risk of rheumatoid arthritis.

Objectives: To analyse the association between female hormonal factors and the development of systemic autoimmunity associated with RA in women at increased risk for RA, namely first-degree relatives of patients with RA (RA-FDRs). Methods: In an ongoing cohort study of RA-FDRs, we analysed all women with available ACPA status. The primary outcome was ACPA positivity. The predictors of interest were female hormonal factors, such as oral contraceptives, breastfeeding, post-menopausal status, early post-menopausal period and total number of ovulatory years. Results: A total of 768 female RA-FDRs were analysed, of which 42 (5%) had developed ACPA positivity. ACPA-positive women were older (52 vs 44 years, P = 0.001). Hormonal factors significantly and independently associated with the presence of ACPA were the post-menopausal (P < 0.001) and the early post-menopausal periods (P = 0.040). Conclusions: In women at increased risk of RA, characteristic systemic autoimmunity was associated with menopause, suggesting that the acute decline in ovarian function might contribute to the development of autoimmunity associated with RA and potentially to the increased risk of RA in women.