Fragility fracture site is associated with frailty in older adults: a population-based cohort study in Japan.

BACKGROUND: Fragility fractures cause disability in older adults. Although frailty determines adverse outcomes, the relationship between anatomical fracture site and functional status remains unclear. Clarifying these associations may improve geriatric assessment and secondary prevention strategies. METHODS: We conducted a population-based retrospective cohort study using the Shizuoka Kokuho Database, which integrates medical and long-term care insurance claims in Japan. Individuals aged ≥65 years with a first-time, single-site fragility fracture (proximal humerus, distal radius, hip, distal femur, vertebrae or pelvis) were included. Frailty was assessed using long-term care insurance (LTCI) certification levels and the electronic frailty index (eFI). Fracture distribution was compared across frailty strata, and crude and age- and sex-adjusted odds ratios (ORs) were estimated using separate logistic regression models for each fracture site. RESULTS: Among 146 052 fractures (mean age 81.5 years; 78.2% women), distal radius fractures occurred predominantly in individuals without LTCI certification (86%), whereas 47% of hip fractures occurred in this group, showing a functional gradient. Distal femur fractures were associated with severe frailty (OR 10.55, 95% CI 9.61-11.57). Age- and sex-adjusted analyses attenuated these associations, but key patterns for distal radius, hip and distal femur fractures remained. Similar gradients were observed across eFI categories. CONCLUSIONS: Fracture site was associated with differences in care needs and frailty among older adults. Distal radius fractures were more common among individuals with lower care needs, whereas pelvic and distal femur fractures were more common among those with advanced frailty. Anatomical fracture location may provide context in geriatric assessment and prevention strategies. Trial Registration (if applicable): Not applicable.