Menopausal Hormone Therapy and Osteoarthritis Risk: Retrospective Population-Based Study in South Korea

Objectives: This study aimed to investigate the risk of osteoarthritis associated with menopausal hormone therapy (MHT). Methods: This population-based retrospective cohort study used a database of Korean health insurance claims (2007-2020). Females aged ≥ 40 who initiated menopause-related healthcare visits between 2011 and 2014 were identified. The MHT group comprised females aged ≥ 40 who initiated MHT for ≥ 6 months during this period. The non-MHT group comprised females aged ≥ 40 who attended menopause-related healthcare visits but did not receive MHT. To account for potential confounding factors, the two groups were matched at a 1:1 ratio using propensity score matching. Results: A cohort of 453,040 postmenopausal females aged ≥ 40 years was identified, with 26,354 assigned to either the MHT or non- MHT group after propensity matching. The median age was 49 years, and the median follow-up was 8.2 years. The Cox proportional hazards model demonstrated an elevated risk of osteoarthritis with MHT (hazard ratio [HR], 1.154; 95% confidence interval [CI], 1.117-1.193) for knee (HR, 1.148; 95% CI, 1.102-1.195) and other arthritis (HR, 1.205; 95% CI, 1.151-1.261), although not statistically significant for hip arthritis. Tibolone (HR, 1.211; 95% CI, 1.161-1.263), estrogen-progestogen therapy (EPT) (HR, 1.092; 95% CI, 1.048- 1.137), and estrogen therapy (ET) (HR, 1.235; 95% CI, 1.148-1.329) were associated with a higher risk of osteoarthritis compared to non- MHT users. Conclusions: MHT was associated with an increased risk of osteoarthritis, consistently observed across tibolone, EPT, and ET, particularly affecting joints other than the hip, with a trend toward an elevated risk of hip osteoarthritis.