New Study Links Hormone Therapy Formulations to Autoimmune Disease Risk
A large study reveals how hormone therapy formulations affect autoimmune disease risk in menopausal women.
CLEVELAND, Ohio (October 20, 2026) — A recent study highlights the potential implications of hormone therapy formulations on the risk of developing autoimmune diseases in menopausal women. Progestogen, often included in hormone therapy, appears to mitigate some of the risks associated with estrogen-only treatments, as revealed in findings presented at the 2026 Annual Meeting of The Menopause Society in San Diego.
Understanding the Risks
Prior studies have established a correlation between menopausal hormone therapy and a heightened risk of autoimmune diseases. However, the specific impact of progestogen remains somewhat ambiguous. The current research aimed to clarify this by comparing the risks between women receiving only systemic estrogen therapy and those receiving systemic estrogen in combination with progestogen.
Study Design and Results
Utilizing the TriNetX US Collaborative Network, this large-scale study analyzed data from nearly 110,000 menopausal women. The participants were carefully matched via one-to-one propensity scores to enhance the validity of the findings. The research focused on a variety of autoimmune conditions, examining occurrences that arose at least 180 days after the initiation of hormone therapy.
Results indicated that women receiving systemic estrogen alone faced a slightly higher risk of developing composite autoimmune diseases compared to those who also received progestogen, with incidence rates at 4.9% and 4.5% respectively. The hazard ratio for the estrogen-only group was recorded at 1.08, accompanied by a 95% confidence interval ranging from 1.02 to 1.14.
Particularly concerning was the significantly elevated risk associated with specific conditions in the estrogen-only cohort, including:
- Systemic lupus erythematosus
- Rheumatoid arthritis
- Psoriasis
- Psoriatic arthritis
- Multiple sclerosis
- Lichen sclerosus
However, researchers noted that while these associations were significant, the absolute rates of these events and the risk differences were relatively small.
Future Research Directions
As articulated by the lead author Dr. Xuezhi Daniel Jiang, a professor at Drexel University College of Medicine, the findings suggest a nuanced relationship between hormone therapy formulations and autoimmune disease risk. "While the results indicate a modest increase in risk linked to estrogen-only therapy, the differences in absolute terms are small. These results provide a foundation for future research that could further illuminate the immunologic impacts of different hormone therapy options," he stated.
Dr. Stephanie Faubion, the medical director of The Menopause Society, underscored the importance of these kinds of studies, noting their role in guiding future research on how hormone therapies might influence autoimmune diseases, conditions that disproportionately affect women.
Details of the study emphasizing the comparison between systemic estrogen and estrogen-progestogen formulations will be elaborated in the presentation titled "Incident Autoimmune Disease Risk in Systemic Estrogen Versus Estrogen-Progestogen Menopausal Hormone Therapy." Further exploration is essential to better understand the intricate relationship between hormone therapy and autoimmune disease risks.