Racial differences in bone strength.

Osteoporosis has been defined as a systemic skeletal disorder characterized by compromised bone strength predisposing to an increased risk of fracture. The clinical consequences of fracture include short- and long-term morbidity as well as increased mortality. Several authors have examined data from the Health Care Financing Administration and noted that fracture risk, particularly risk of hip fracture, is higher in whites than blacks in both sexes; the most recent published data reported an age-adjusted annual incidence rate for hip fracture of 10.1 and 4.1 per 1000 in white and black women, respectively, and 4.3 and 3.1 per 1000 in white and black men, respectively. Other analyses estimated the actuarial risk of hip fracture of persons age 65 by age 90 to be 16.3 and 5.3 percent in white and black women, respectively, and 5.5 and 2.6 percent in white and black men, respectively. This lower incidence of fractures among blacks has generally been explained by greater bone strength among blacks, although differences in non-skeletal risk factors for fracture, such as falls, cannot be completely excluded. Data from the Study of Osteoporotic Fractures (SOF) and the Baltimore Men's Osteoporosis Study (MOST) show that, in both sexes, blacks have higher adjusted bone mineral density than whites and a slower age-adjusted annual rate of decline in bone mineral density. Genetic, nutritional, lifestyle and hormonal factors may contribute to these ethnic/racial differences in bone strength.