Menopause-Related Changes in Body Composition Are Associated With Subsequent Bone Mineral Density and Fractures: Study of Women's Health Across the Nation.
Level 3 - non-randomized controlled study
Prospective cohort study
PubMed 36542065 · doi:10.1002/jbmr.4759
What was done
Researchers evaluated 539 participants from the Study of Women's Health Across the Nation (SWAN) who were not taking bone-modifying medications during the menopause transition (MT; 2 years before to 2 years after the final menstrual period). Multivariable linear regression examined associations between percent lean mass loss and fat mass gain with femoral neck (FN) and lumbar spine (LS) bone mineral density (BMD) at the end of the MT. Cox proportional hazards regression assessed the relation between body composition changes and post-MT fracture risk, adjusting for baseline BMD, pre-MT body composition, race/ethnicity, study site, age, cigarette use, post-MT bone-detrimental medications, and end-of-MT BMD.
What was found
Each standard deviation (SD; 6.9%) increment in lean mass loss was associated with 0.010 g/cm² lower FN BMD (p < 0.0001). Each SD (19.9%) increment in fat mass gain was associated with 0.026 g/cm² greater FN BMD (p = 0.009) and LS BMD (p = 0.03). In fracture analyses, each SD increment in lean mass loss was associated with a 63% higher fracture hazard (p = 0.001), and each SD increment in fat mass gain was associated with a 28% higher fracture hazard (p = 0.05). These fracture associations were essentially unchanged after adjustment for end-of-MT BMD.
Why it matters
This study shows that body composition changes across the menopause transition independently predict subsequent fracture risk. Gaining fat mass confers higher BMD but paradoxically increases fracture hazard, highlighting that bone density alone does not capture fracture risk related to changes in adiposity and muscle mass.
Limits
The study is observational, leaving potential for unmeasured confounding. The abstract does not specify fracture sites, fall rates, physical activity levels, or dietary intake, and participants taking bone-active medications during the transition were excluded, which may limit generalizability.