Bone Abstracts

Vertebral fracture assessment (VFA) by DXA is an accepted tool in adults. However, its use in children has not been validated. The aim of this study was to validate VFA using iDXA against spinal radiographic assessment (RA) for the identification of vertebral fractures in children.

Spine radiographs and VFA (L5–T2) by GE-iDXA were acquired on the same day in 80 children. Forty children were considered high-risk for fracture as their metabolic bone specialist had initiated a referral for a radiographic spine assessment. The remaining 40 subjects consisted of children participating in a prospective fracture study and were considered low-risk for vertebral fracture. Agreement between RA and VFA was assessed by an expert paediatric radiologist and two metabolic bone specialists. Vertebrae were ranked as normal, mild, moderate or severe if they had <10, 11–25, 26–50, and >50% deformity respectively. Levels of agreement were calculated using the kappa statistic and consistency by the intra-class correlation coefficient (ICC).

Depending on rater, 92.8–94.8% of the vertebrae were analysable by RA. In contrast, 98.5% were analysable by VFA. For the high-risk group, moderate agreement was noted between raters for RA (κ 0.496–0.556), between RA and VFA (κ 0.510–0.586) and between raters for VFA (κ 0.0.630–0.687). In contrast, for the low-risk group, where only mild deformities were observed, poor-to-slight agreement was noted between raters for RA (κ 0.075–0.2116) and slight-to-fair agreement was noted between RA and VFA (κ 0.100–0.365) and between raters for VFA (κ 0.308–0.343). In the high-risk group, agreement improved to substantial if the deformities were dichotomised as normal or mild vs moderate or severe (κ 0.810–879). Subsequently, diagnostic agreement was tested by categorising each subject as having at least one severe or at least one moderate, mild only or no deformity. This approach resulted in consistent levels of moderate agreement between rater and technique (κ 0.483–0.645).

In conclusion, VFA is accurate and consistent when identifying moderate and severe fractures in chronically sick children. However, since the diagnostic sensitivity of VFA appeared to be comparable to RA for both groups, VFA should prove to be a useful tool in the assessment of bone health in all children.