LAUSR

It is commonly assumed that high oestradiol levels in women are cardioprotective. We assessed the association between oestradiol and the risk of incident myocardial infarction in women. We used data from 263,295 female UK Biobank participants (mean age 56.2; SD 8.0 years) without prior cardiovascular disease. Associations of oestradiol with age and other cardiovascular risk factors were assessed. Cox proportional hazards models estimated crude, age, and multiple-adjusted hazard ratios (HR) for MI associated with oestradiol levels. After a mean follow-up of 9 years, 2,206 incident cases of MI had been recorded, including 230 events among the 57,204 women (mean age 48) with detectable oestradiol levels. In the unadjusted analyses, a unit higher in log-transformed oestradiol was associated with a HR (95% CI) for MI of 0.73 (0.58; 0.92). After adjusting for age this HR became 0.94 (0.75; 1.17), and after further adjusting for classical CVD risk factors, 1.05 (0.83; 1.31. Results were similar in subgroup analyses defined by age, menopausal status, socioeconomic status, pill use, and the use of hormone replacement therapy. The multivariable adjusted HR for the 171,431 women (mean age 59) with undetectable levels of oestradiol, compared to those with detectable levels, was 0.97 (0.92; 1.02). Higher levels of oestradiol were not associated with a decreased risk of MI. The presumed cardioprotective effects of oestradiol seem to be largely confounded by age, and further confounded by other cardiovascular risk factors. Figure 1 Type of funding source: None