Bone Abstracts

Objectives: Bone mineral density (BMD) in children is generally measured with dual energy X-ray absorptiometry (DXA). Digital X-ray Radiogrammetry (DXR) is a promising alternative technique, that uses BoneXpert software to measure cortical BMD on hand radiographs, expressed as bone health index (BHI). DXR is a cheap method, is easy to apply in every hospital and involves less ionizing radiation compared to DXA. We aim to compare DXR and DXA measurements for determining bone density in children with high probability of secondary low BMD or osteoporosis.

Methods: This prospective study included all children visiting the Radboudumc Amalia Children’s hospital between July 2016 and 2018 that underwent both DXA of the lumbar spine (DXALS) and DXR within a 3 months’ period. Patients were excluded if either DXALS or DXR could not be assessed. DXA Z-scores were also corrected for bone age (BAZ-scores) with BoneXpert. Low BMD was defined as (BA)Z-score ≤−2.0. DXR Z-scores were compared to DXA (BA)Z-scores as the golden standard, using Pearson correlations, Bland-Altman analysis and a sensitivity-specificity analysis.

Results: Sixteen (15%) out of 107 patients were excluded, leaving 91 individuals for analyses. Mean bone age, and DXR and DXA (BA)Z-scores, were significantly impaired compared to a healthy reference population. Pearson correlation coefficients were significant between DXR Z-scores and both DXALS (BA)Z-scores: 0.495–0.536 (P<0.001). Bland-Altman analyses showed good agreement between DXR and DXALS (BA)Z-scores. Percentage similarity showed good agreement, mostly for (BA)Z-scores ≤−2.0. DXR had a sensitivity of 69–71% and specificity of 74–80% compared to DXALS (BA)Z-scores.

Conclusion: DXR correlates well with DXALS (BA)Z-scores and showed good agreement with DXALS, especially for (BA)Z-scores ≤−2.0. DXR shows best results when compared with DXALS Z-scores. DXR is a promising alternative for diagnosing low BMD in children with high probability of secondary impaired bone density.

Disclosure: The authors declared no competing interests.