Menopausal hormone therapy and risk of seropositive rheumatoid arthritis: A nationwide cohort study in Korea.

OBJECTIVES: This retrospective cohort study aimed to investigate the impact of menopausal hormone therapy (MHT) on the incidence of rheumatoid arthritis (RA) in postmenopausal women and to examine the effects of each specific MHT drug.

METHODS: In this Korean population-based cohort study, 452,124 women aged > 40 years who consulted a healthcare provider for menopause were evaluated from January 1, 2011, to December 31, 2014. After propensity score matching, 138,991 pairs were included in the MHT and non-MHT groups. Participants were followed up until December 31, 2020. RA was defined according to the International Classification of Diseases, 10th edition, limited to seropositive RA (M05).

RESULTS: RA developed in 567 (0.4 %) of the 138,424 patients in the MHT group. The RA risk in the MHT group was not significantly increased compared with that of controls (hazard ratio [HR] 1.12, 95 % confidence interval [CI] 0.998-1.256). However, MHT use for ≤ 3 years was associated with an increased risk of RA (HR 1.277, 95 % CI 1.127-1.447). When estrogen/progestogen was used, the HR was 1.24 (95 % CI 1.05-1.46), whereas when tibolone was used, the HR was 1.33 (95 % CI 1.13-1.57).

CONCLUSION: The use of MHT did not show a significant impact on the development of RA in postmenopausal women. However, a subanalysis that specifically examined the duration of MHT revealed a noteworthy increase in the risk of RA during the initial 3 years of MHT use.