Distal Radial Fracture as an Early Marker of Bone Fragility: A Population-Based Study in Japan.

BACKGROUND: Distal radial fractures (DRFs) are common fragility fractures in older adults and often indicate skeletal deterioration. However, whether DRFs reflect underlying systemic frailty or occur predominantly in relatively active individuals with preserved physical function remains unclear.

METHODS: This retrospective cohort study analyzed data from the Shizuoka Kokuho Database, which includes the health and long-term care (LTC) claims of 2.4 million residents. Individuals aged 65 to 89 years who were newly diagnosed with a DRF between 2012 and 2022 were compared with patients with an upper-limb contusion. Propensity score matching was used to balance baseline characteristics between these groups. The primary outcome was all-cause mortality. The secondary outcomes included secondary fragility fractures, hospitalization, LTC deterioration, and osteoporosis treatment initiation. Cox proportional hazards and Poisson regression models were used for the analysis. Causal mediation analysis was conducted to explore the indirect effects of secondary fractures and treatment initiation.

RESULTS: After propensity score matching, the final analysis included 47,178 patients (23,589 matched pairs; mean age, 77.6 ± 6.7 years; 87.8% female) with balanced baseline characteristics. In the matched cohort, patients with a DRF had lower all-cause mortality than controls in the unadjusted analysis (hazard ratio [HR], 0.90; 95% confidence interval [CI], 0.86 to 0.94), but this association was attenuated after multivariable adjustment that included baseline LTC certification (HR, 0.98; 95% CI, 0.93 to 1.02). Subgroup analysis showed that a DRF was associated with lower mortality among individuals with higher LTC needs, particularly women. In the matched cohort, patients with a DRF had higher rates of subsequent hip fractures (2.58 [95% CI, 2.48 to 2.69] versus 2.00 [95% CI, 1.91 to 2.10] fractures per 100 person-years) and more frequent osteoporosis treatment initiation within 1 year after injury (17.6% [95% CI, 17.1% to 18.1%] versus 7.7% [95% CI, 7.4% to 8.0%] of patients). The mediation analysis suggested modest indirect effects of secondary hip fractures and vitamin-D supplementation on mortality.

CONCLUSIONS: DRFs in older adults may reflect preserved function and skeletal fragility rather than advanced frailty. These fractures may represent a critical window for initiating osteoporosis treatment to prevent subsequent fractures and improve long-term outcomes.

LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.