Family history and risk of osteoporotic fracture. Study of Osteoporotic Fractures Research Group.

The importance of family history of fractures as a risk factor for fractures is unclear. The aim of this study was to test the hypothesis that family history of fracture increased a woman's risk of hip, wrist and other osteoporotic fracture and determine whether the influence of family history is independent of low bone density. We tested this hypothesis in a prospective study of 9704 Caucasian women, age 65 years or older, by assessing family history and bone density of the radius and calcaneus at baseline; 7963 women had femoral bone density measurements two years later. Fractures occurring during an average of 7.1 years of follow-up since baseline and 5.2 years since the second examination were confirmed by radiographic report. After adjusting for age, risk of hip fracture was increased in those with a maternal (1.48; 95% CI = 1.03-2.11); sister's (1.83; 1.20-2.80) or brother's history of hip fracture (2.26; 1.16-4.42). Risk of wrist fracture was increased by maternal (1.52; 1.10-2.11) and paternal (2.41; 1.14-5.07) history of wrist fracture. Adjustment for bone density did not consistently and substantially affect the strength of the associations. Family history of hip fracture was not associated with an increased risk of wrist fracture and family history of wrist fracture did not increase the risk of hip fracture. We conclude that family history is an important risk factor for fracture that may act, at least in part, through means besides bone density. Furthermore, the effect of family history is not a general but site-specific predisposition to fracture.