Exploring the risk of venous thromboembolism in women with rheumatoid arthritis initiating menopausal hormone treatment in England.

OBJECTIVES: While RA and menopausal hormone treatment (MHT) are known to increase the risk of venous thromboembolism (VTE), how MHT influences VTE incidence within the RA population has not been well-characterised. This study aimed to evaluate whether MHT is associated with an increased risk of VTE in peri- and postmenopausal women with RA. METHODS: We conducted a retrospective, matched cohort study using UK primary care data from the Clinical Practice Research Datalink (CPRD) Aurum, linked to secondary care, from 2001 to 2021. Women ages 40-79 years with RA initiating MHT were matched to women with RA not initiating MHT. VTE incidence rates were calculated and Cox proportional hazards models adjusted for risk factors estimated the MHT-associated VTE risk. RESULTS: A total of 2187 women with RA initiating MHT were matched to 8205 unexposed controls. VTE incidence was higher among MHT users [6.49 (95% CI 4.28, 9.44) per 1000 person-years vs 3.30 (95% CI 2.44, 4.36)]. MHT use was associated with a 92% increased risk of VTE in RA [adjusted hazard ratio (aHR) 1.92 (95% CI 1.19, 3.12)], primarily driven by a higher risk of deep vein thrombosis [DVT; aHR 2.26 (95% CI 1.26, 4.05)]. CONCLUSION: MHT use in peri- and postmenopausal women with RA is associated with a 2-fold increased risk of VTE, particularly DVT, relative to unexposed controls. Individualised risk assessment and monitoring are advised, taking into account the patient's clinical context. Clinicians should balance MHT benefits against thrombotic risks and consider alternatives or preventive strategies.