Relationship between higher estradiol levels and 9-year mortality in older women: the Invecchiare in Chianti study.

OBJECTIVES: To investigate the relationship between total estradiol (E2) levels and 9-year mortality in older postmenopausal women not taking hormone replacement therapy (HRT). DESIGN: Population-based study of persons living in the Chianti geographic area (Tuscany, Italy). SETTING: Community. PARTICIPANTS: A representative sample of 509 women aged 65 and older with measures of total E2. MEASUREMENTS: Serum total E2 was measured at the University of Parma using ultrasensitive radioimmunoassay (RIA). RESULTS: Women who died (n=135) during 9 years of follow up were older; had higher total E2 levels; and were more likely to have evidence of stroke, hypertension, diabetes mellitus, and congestive heart failure at baseline than survivors. Higher E2 levels were associated with a greater likelihood of death (hazard ratio (HR)=1.03, 95% confidence interval (CI)=1.01-1.06), and the relationship was independent of age, waist:hip ratio, C-reactive protein, education, cognitive function, physical activity, caloric intake, smoking, and chronic disease (HR=1.08 pg/mL, 95% CI=1.03-1.13, P=.003). The excessive risk of death associated with higher total E2 was not attenuated after adjustment for total testosterone (HR=1.12, 95% CI=1.02-1.18, P<.001) and after further adjustment for insulin resistance evaluated using the homeostasis model assessment (HR=1.07, 95% CI=1.03-1.17, P<.001). Total E2 was highly predictive of death after more than 5 years (HR=1.42: CI 1.01-1.91, P=.04) and not predictive of death for less than 5 years (P=.78). CONCLUSION: Higher total E2 concentration predicts mortality in older women not taking HRT