Associations between ultra-distal forearm bone mineral density and incident fracture in women

Bone mineral density measured at the ultra-distal forearm site was associated with any fracture, as well as distal radius fracture in women from a longitudinal cohort study. Femoral neck (BMDhip) and lumbar spine (BMDspine) bone mineral density (BMD) are routinely used to assess fracture risk. More data are needed to understand how ultra-distal forearm BMD (BMDUDforearm) may assist fracture prediction. Using a Lunar DPX-L, Geelong Osteoporosis Study women (n = 1026), aged 40–90 years, had BMD measured. Incident low-trauma fractures were radiologically verified. Using Cox proportional hazard models, hazard ratios (HR) were calculated for BMDUDforearm as a continuous variable (expressed as a one-unit decrease in T-score) and a categorical variable (normal/osteopenia/osteoporosis). Areas under receiver operating characteristics (AUROC) curves were calculated. Analyses were conducted for any fracture and distal radius fractures. During 14,270 person-years of follow-up, there were 318 fractures (85 distal radius). In adjusted models, continuous BMDUDforearm was associated with any (HR 1.26;95%CI 1.15–1.39) and distal radius fractures (HR 1.59;95%CI 1.38–1.83). AUROCs for continuous BMDUDforearm, 33% forearm(BMD33%forearm), BMDhip, BMDspine, and FRAX without BMD were similar for any fracture (p > 0.05). For distal radius fracture, the AUROC for BMDUDforearm was higher than other sites and FRAX (p < 0.05). In adjusted models, those with osteoporosis had a higher likelihood of any fracture (HR 2.12; 95%CI 1.50–2.98). For distal radius fractures, both osteopenia and osteoporosis had a higher risk (HR 4.31; 95%CI 2.59–7.15 and 4.81; 95%CI 2.70–8.58). AUROCs for any fracture were similar for categorical BMD at all sites but lower for FRAX (p < 0.05). For distal radius fractures, the AUROC for BMDUDforearm, was higher than other sites and FRAX (p < 0.05). Ultra-distal forearm BMD may aid risk assessments for any distal radius fractures.