Estrogen effects on postural balance in postmenopausal women without vasomotor symptoms:: A randomized masked trial

Objective: To assess whether estrogen treatment given to postmenopausal women without vasomotor symptoms improves balance more than placebo. Methods: Forty healthy postmenopausal women without vasomotor symptoms were randomized to transdermal 17 beta-estradiol (E2) 50 mu g/day for 14 weeks or identical transdermal placebo patches. Postural balance was measured with dynamic posturography before and after 4, 12, and 14 weeks of therapy. In this test, the visual, vestibular, and somatosensory systems were provoked with increasing difficulty and body sway was measured with a dual forceplate. A low score showed large sway and a score of 100 showed no sway at all. Results: Thirty-eight women completed the study, both groups had normal balance for their ages and near maximum scores in the three easier balance tests at baseline. Ln the most difficult test, both groups improved their postural balance significantly (from 13 to 32 and from 22 to 39, respectively) after 4 weeks. Thereafter, no change was seen. One problem was low statistical power, but the relative change in balance did not differ between groups. The comparison did not show even a minute advantage of E2 over placebo, so a study with higher power would probably not have shown a more pronounced effect of estrogen than placebo. The change over time did not differ between groups, which indicates a significant learning effect. Conclusion: In women without vasomotor symptoms, estrogen therapy did not seem to increase postural balance significantly more than placebo, However, we could not rule out that estrogens affect postural balance in women with vasomotor symptoms. (Obstet Gynecol 2000;95:278-83. (C) 2000 by The American College of Obstetricians and Gynecologists.).