Hormone replacement therapy and longitudinal changes in blood pressure in postmenopausal women

Background: The incidence of hypertension in postmenopausal women exceeds that in age-matched men. Longitudinal studies relating hormone replacement therapy (HRT) to blood pressure changes are sparse. Objective: To investigate the association between HRT and longitudinal changes in blood pressure in postmenopausal women. Design: Longitudinal observational study. Setting: Community-dwelling volunteers. Patients: 226 healthy, normotensive postmenopausal women from the Baltimore Longitudinal Study of Aging with a mean (±SD) age of 64 ± 10 years were followed for 5.7 ± 5.3 years. Seventy-seven women used both estrogen and progestin, and 149 used neither. Measurements: Lifestyle variables, blood pressure, and traditional cardiovascular risk factors were measured at baseline and approximately every 2 years thereafter. Results: Systolic blood pressure at baseline was similar in HRT users and nonusers (133.9 ± 16.0 mm Hg vs. 132.4 ± 14.8 mm Hg). Over time, average systolic blood pressure increased less in HRT users than nonusers, independent of other cardiovascular risk factors, physical activity, and alcohol use. For example, HRT users who were 55 years of age at their first Baltimore Longitudinal Study of Aging visit experienced a 7.6-mm Hg average increase in systolic blood pressure over 10 years; in contrast, the average increase in nonusers was 18.7 mm Hg. The lesser increase in systolic blood pressure in HRT users was more evident at older age. Diastolic blood pressure, which did not change statistically over time in either group, was not associated with HRT. Conclusion: Postmenopausal women taking HRT have a smaller increase in systolic blood pressure over time than those not taking HRT. This difference is intensified at older ages.