Longitudinal changes in hip geometry in relation to the final menstrual period: Study of Women's Health Across the Nation (SWAN).

Abstract

In SWAN, we showed that accelerated loss of bone mineral density (BMD) begins 1 year before the final menstrual period (FMP) to 2 years after the FMP and slows thereafter. However, the risk of fracture depends on both BMD and bone geometry. The hip structural analysis (HSA) measures important geometric properties of bone. Changes in HSA parameters across the menopausal transition have not been previously assessed. The current analysis uses data from SWAN, 5 years before to 5 years after FMP (N = 900, Age (mean(SD)) = 46.85(2.60), 44% White). HSA parameters at the femoral narrow neck were obtained from 2D DXA scans and normalized to baseline values. FMP was determined from annual interviews. Changes in HSA were assessed over 3 periods, 5 to 2 years before FMP (pre-transmenopausal), 2 years before to 1 years after FMP (transmenopausal), 1 to 5 years after FMP (postmenopausal). Mixed linear models with random slopes were used to estimate the rate of change in HSA parameters relative to FMP. Loss of BMD, cross-sectional area (CSA), and section modulus (SM) and increases in outer diameter (OD) were greatest in the transmenopausal period (p for all<0.05). Changes continued in the postmenopausal period but were not statistically significant. The cumulative percentage changes over 10 years in BMD (-10.67%), CSA (-9.01), SM (-7.03) and OD (+1.95) were statistically significant. Changes in hip geometry across the menopause transition parallel changes in BMD and provide insight into mechanisms that may increase risk of fragility fracture.