Fracture risk in 85-year-old women: associations with volumetric bone mineral density, physical performance and falls

Summary This prospective study demonstrates associations of volumetric BMD (vBMD) by pQCT, areal BMD (aBMD) by DXA, physical performance (one-leg balance, gait speed, and knee extension force), and fall history with fracture risk in 85-year-old women. A failed one-leg balance test was associated with both hip and any fracture independent of femoral neck aBMD. Total radial vBMD was associated with any fracture. Gait speed and previous falls showed associations with fracture risk of similar magnitude as femoral neck aBMD. These findings suggest that functional performance measures may enhance fracture risk assessment in older women. Purpose This prospective study evaluates associations between fracture risk and volumetric bone mineral density (vBMD) by peripheral quantitative computed tomography (pQCT), physical performance tests, and fall history, in comparison with femoral neck areal BMD (aBMD) by DXA, in 85-year-old women. Methods In the Osteoporosis Prospective Risk Assessment (OPRA) study, 382 women aged 85 years were followed for a mean of 4.3 years. Participants underwent pQCT of the radius and tibia and DXA of the hip and lumbar spine, performed physical performance tests (one-leg standing balance, considered failed if balance could not be maintained for 5 s; gait speed, analyzed continuously; and knee extension force, measured by isometric dynamometry), and reported fall history. Cox proportional hazards models estimated fracture risk, adjusting for BMI, previous fracture, smoking, and use of vitamin D, glucocorticoids, and bisphosphonates. Results During a mean follow-up of 4.3 years, 116 women (30%) sustained a fracture. Trabecular vBMD at the radius and tibia was associated with lower risk of any fracture (HR 0.68, 95% CI 0.55–0.85 and HR 0.69, 95% CI 0.55–0.86, respectively). Radial trabecular vBMD was also associated with lower hip fracture risk (HR 0.64, 95% CI 0.42–0.98). Femoral neck aBMD was associated with lower risk of any fracture (HR 0.75, 95% CI 0.62–0.90), but not hip fracture (HR 0.71, 95% CI 0.50–1.00). A failed balance test and low gait speed was associated with higher risk of any fracture (HR 1.55, 95% CI 1.04–2.29 and HR 1.22, 95% CI 1.01–1.48, respectively). In multivariate analyses, a failed balance test remained associated with any fracture (HR 1.70, 95% CI 1.12–2.56) and hip fracture (HR 2.30, 95% CI 1.05–5.02). Total radial vBMD remained associated with any fracture (HR 0.79, 95% CI 0.63–0.996). Conclusion Volumetric BMD by pQCT was associated with fracture risk independent of commonly recognized clinical risk factors in 85-year-old women. Physical performance tests were associated with fracture risk in unadjusted analyses, and the one-leg balance test additionally remained associated after adjustment for clinical risk factors and femoral neck aBMD.