Clalit study of 52,000 women links modern hormone therapy to no rise in heart risks

An observational study of electronic health records from Israel's Clalit Health Services evaluated modern hormone replacement therapy in over 52,000 women, knowridge.com reported. The research, led by Ronen Arbel of Clalit and Sapir College, assessed whether initiating treatment between ages 45 and 59 correlated with adverse cardiovascular outcomes over an average follow-up of 12 years, with some records extending to 23 years. The preliminary findings are scheduled for presentation at the American Heart Association Scientific Sessions 2026 knowridge.comknowridge.comknowridge.comOpen source ↗.

Cohort matching and clinical outcomes

The investigators compared women who initiated hormone therapy with those who visited a gynecologist but did not begin treatment. The analysis excluded individuals with documented histories of heart disease, blood clots, or cancer. Researchers matched the cohorts across several baselines, including age, body mass index, blood pressure, cholesterol levels, diabetes status, smoking habits, and socioeconomic status. Monitored endpoints included myocardial infarction, stroke, related cardiovascular conditions, blood clots, and mortality before age 80 knowridge.comknowridge.comknowridge.comOpen source ↗.

Formulations and observational limitations

According to the authors, cardiovascular and mortality outcomes were comparable between the hormone therapy group and the non-treatment group knowridge.comknowridge.comknowridge.comOpen source ↗. This pattern remained consistent across several administration routes and formulations, including oral tablets, transdermal patches, and topical gels. The authors noted that prior historical studies frequently examined older demographics or different drug formulations knowridge.comknowridge.comknowridge.comOpen source ↗.

Because the investigation relies on retrospective health records rather than a randomized trial, it does not confirm a lack of excess risk. Unmeasured confounding variables, such as exercise habits, diet, comorbid conditions, and menopausal symptom severity, were not fully accounted for in the dataset. Additionally, subjects were categorized based on their initial prescription without continuous tracking of dosage adjustments or formulation shifts over time knowridge.comknowridge.comknowridge.comOpen source ↗.