Abstract
Objectives: To examine risk factors for fracture in a racially diverse cohort of healthy children in the US. Study design: A total of 1470 healthy children, aged 6-17 years, underwent yearly evaluations of height, weight, body mass index, skeletal age, sexual maturation, calcium intake, physical activity levels, and dual-energy x-ray absorptiometry (DXA) bone and fat measurements for up to 6 years. Fracture information was obtained at each annual visit, and risk factors for fracture were examined using the time-dependent Cox proportional hazards model. Results: The overall fracture incidence was 0.034 fracture per person-year with 212 children reporting a total of 257 fractures. Being white (hazard ratio [HR] = 2.1), being male (HR = 1.8), and having skeletal age of 10-14 years (HR = 2.2) were the strongest risk factors for fracture (all P ≤ .001). Increased sports participation (HR = 1.4), lower body fat percentage (HR = 0.97), and previous fracture in white girls (HR = 2.1) were also significant risk factors (all P ≤ .04). Overall, fracture risk decreased with higher DXA z scores, except in white boys, who had increased fracture risk with higher DXA z scores (HR = 1.7, P <.001). Conclusions: Boys and girls of European descent had double the fracture risk of children from other backgrounds, suggesting that the genetic predisposition to fractures seen in elderly adults also manifests in children.