Objective: Postmenopausal hormone therapy (HT) results in more substantial reductions in the risk of hip fracture when initiated sooner rather than later after menopause. We studied the effects of postmenopausal HT on the postural balance of postmenopausal women, with further assessment according to the time since they achieved menopause.
Design: One hundred women with a mean age of 52.5 years (91 evaluable) were randomly and blindly assigned to either a sequential estradiol-norethisterone acetate regimen or placebo for 3 months, after which all participants received open HT for a further 3 months. Postural balance was assessed as sway velocity using a force platform.
Results: After 3 months of HT, sway velocity had improved (decreased) from baseline by 7.0% (P = 0.007 vs baseline and P = 0.038 vs placebo). Continued HT for 6 months further improved sway velocity by 12% from baseline (P < 0.0001) to reach values similar to those historically found in younger women or in postmenopausal women after long-term HT. Closer proximity to menopause and more pronounced increases in serum estradiol values were associated with stronger improvements in sway velocity (P = 0.018 for interaction). HT also improved dizziness (P = 0.016 vs baseline and 0.022 vs placebo). (Nonparametric statistics are used throughout, except for analyses of interaction and dizziness.)
Conclusions: Initiation of HT soon after menopause rapidly improved postural balance to levels normally seen in young women. We suggest that improved postural balance can contribute to the protection against fractures associated with HT and explain the more substantial reduction in hip fracture risk after HT initiated sooner, compared with later, after menopause. Further study is required to confirm these results.