The effects of menopausal hormone therapy for the risk of systemic lupus erythematosus: A nationwide cohort study in Korea

Objectives: This retrospective cohort study aimed to investigate the influence of menopausal hormone therapy (MHT) on the occurrence of systemic lupus erythematosus (SLE) in postmenopausal women. Additionally, the study aimed to examine the specific effects of individual MHT drugs. Methods: In this population-based cohort study conducted in Korea, a total of 452,124 women aged >40 years seeking healthcare for menopause were assessed from January 1, 2011, to December 31, 2014. After employing propensity score matching, 139,331 pairs were included in the MHT and non-MHT groups. Follow-up of participants continued until December 31, 2020. The diagnosis of SLE was based on the International Classification of Diseases 10th edition criteria. Results: The median follow-up in the study was 7.9 [6.9-8.9] years. SLE developed in 134 (0.1 %) of the 139,197 participants in the MHT group and 143 (0.1 %) of the 139,188 of the non-MHT group, individually. The risk of SLE in the MHT group did not show a significant increase compared to the non-MHT group {hazard ratio (HR) 1.114, 95 % confidence interval (CI) 0.88-1.41}. Subgroup analysis results indicated no significant differences based on the type of MHT or the duration of MHT use, except tibolone. In the group that used tibolone within 3 years, the HR for SLE risk was 1.45 (95 % confidence interval: 1.051-2.001). Conclusion: The utilization of MHT did not demonstrate a substantial impact on the development of SLE in postmenopausal women. Caution is required in the early stages of tibolone use.