Can BMD assessed by DXA at age 8 predict fracture risk in boys and girls during puberty?: an eight-year prospective study

Abstract

This study reports on the association between DXA at age 8 and subsequent fractures in both male and female children. Bone densitometry at the total body and spine (but not hip) is a strong predictor of fracture (especially upper limb) during puberty.

Introduction: The aim of this study was to determine if prepubertal DXA can predict fracture risk during puberty.

Materials and methods: We studied 183 children who were followed for 8 yr (1460 person-years). Bone densitometry was measured at the total body, hip, and spine by DXA and reported as BMC, BMD, and bone mineral apparent density (BMAD). Fractures were self-reported at age 16 with X-ray confirmation,

Results: There were a total of 63 fractures (43 upper limb). In unadjusted analysis, only total body BMD showed an inverse relationship with upper limb fracture risk (p = 0.03). However, after adjustment for height, weight, age (all at age 8), and sex, total body BMC (HR/SD, 2.47; 95% CI, 1.52-4.02), spine BMC (HR/SD, 1.97: 95% CI, 1.30-2.98), total body BMD (HR/SD, 1.67; 95% CI, 1.18-2.36), total body BMAD (HR/SD, 1.54; 95% CI, 1.01-2.37), and spine BMD (HR/SD, 1.53; 95% CI, 1.10, 2.22) were all significantly associated with upper limb fracture risk. Similar, but weaker associations were present for total fractures. There was a trend for overweight/obesity to be associated with increased upper limb fracture risk (HR, 1.53/category; p = 0.08).

Conclusions: Measurement of bone mass by DXA is a good predictor of upper limb fracture risk during puberty. Although we did not measure true BMD, the constancy of fracture prediction after a single measure suggests bone strength remains relatively constant during puberty despite the large changes in bone size.