Appendicular bone mineral and a woman's lifetime risk of hip fracture.

Appendicular bone mass is inversely related to the risk of hip fracture in short-term prospective studies, but hip fractures typically occur about 30 years after menopause. We developed a model that estimates a woman's lifetime risk of hip fracture based on measurement of radial bone mass at age 50 using short-term prospective data relating bone mass to hip fracture, the correlation between bone mass at age 50 and later years, the age-specific incidence of hip fracture and mortality, and prospective data about bone mass and mortality. We estimate that a 50-year-old white woman has a 19% lifetime risk of hip fracture if her radial bone mass is at the 10th percentile for her age and an 11% lifetime risk if her bone mass is at the 90th percentile. Improved measurement techniques that have a higher predictive value for hip fracture in short-term studies could substantially increase this gradient of lifetime risk and therefore be more clinically useful.