Bone health and body composition in pre-frail and frail older adult women: insights from high-resolution peripheral quantitative computed tomography (HR-pQCT)

BACKGROUND: Age-related muscle loss and obesity are linked to poor bone health and increased fracture risk, though findings in frail populations are inconsistent. This study examined differences in bone microarchitecture across body composition phenotypes in frail older women. METHODS: In this cross-sectional study, 280 older women were included, 109 of whom met Fried frailty criteria. Body composition was assessed using dual-energy X-ray absorptiometry and classified into four groups: low appendicular lean mass (LALM; <20th percentile of residuals), obesity (fat mass index >13 kg/m²), obesity with LALM, or neither. Bone microarchitecture was measured by high-resolution peripheral quantitative computed tomography (HR-pQCT). Analyses used generalized estimating equations with Bonferroni correction, χ² tests, and Fisher's exact tests. RESULTS: Compared with the obesity group, women with LALM had smaller cortical area and thinner cortex at both the tibia and radius. At the radius, the LALM group also showed lower cortical area and thickness, total volumetric bone mineral density, and trabecular number, as well as greater trabecular area and separation, compared with the obesity plus LALM group. Bone strength was significantly lower in the LALM group than in the obesity and obesity plus LALM groups. CONCLUSIONS: Among pre-frail and frail older women, obesity was associated with more favorable cortical and trabecular bone microarchitecture compared with low muscle mass without obesity. Excess adiposity may partially mitigate skeletal deterioration. Longitudinal studies are needed to clarify the impact of body composition on fracture risk in frail older adults.