Objective: To assess the effect of reproductive factors, especially hormonal replacement therapy (HRT) and its interaction with HLA-DRB1 *01 and/or *04 alleles on the diagnosis of RA and the presence of anti-CCP in women included in the ESPOIR cohort (early arthritis cohort).
Methods: 568 patients were included in the analyses. Analyses were performed using logistic regression.
Results: HRT would reduce the risk for RA due to the HLA-DRB1 *01 and/or *04 alleles: from OR=1.88 (95%CI 1.32-2.68, p<0.000) for HLA-DRB1 *01 and/or *04 alleles alone to OR=1.07 (0.51-2.26, p=0.85) in women who carry HLA-DRB1 *01 and/or *04 alleles and who received a HRT. One explanation would be the protective effect of HRT on the presence of anti-CCP (OR=0.43, 95%CI 0.24-0.77, p<0.006). Other reproductive factors such as the number of pregnancies, menopause, and age of the menopause, age of the menarche and a history of pregnancy with poor outcome were not associated with the diagnosis of RA and the presence of anti-CCP.
Conclusion: HRT may reduce the risk of RA due to HLA-DRB1 *01 and/or *04 alleles by protecting against the production of anti-CCP.