Bone Health in Children With Intestinal Failure Measured by Dual Energy X-Ray Absorptiometry and Digital X-Ray Radiogrammetry

Abstract

Introduction: Children with intestinal failure (IF) receiving parenteral nutrition (PN) are at risk of developing a low bone mineral density (BMD). Next to the use of dual energy X-ray absorptiometry (DEXA), digital X-ray radiogrammetry (DXR) using BoneXpert® software has become available to obtain a Bone Health Index (BHI) in hand radiographs. Advantages are the availability of normative data for infants and the direct adjustment for bone age. Our aims were to 1) evaluate the prevalence of low BMD measured by DEXA and DXR and 2) to compare these methods in the assessment of low BMD in children with IF. Methods: A retrospective study was performed in all children with IF treated from 2000 to 2015 by the IF-team of Sophia Children’s Hospital Rotterdam, who had undergone a DEXA scan and/or a hand radiograph. Z-scores of BMD total body (BMDTB), lumbar spine (BMDLS) and BHI were collected. Low BMD and BHI were defined as Z-scores ≤ −2. DEXA and DXR results were compared for cases in which a DEXA and hand radiograph were performed within a 6 months’ interval. Results: Forty-six children were included. Twenty-one children (46%) had short bowel syndrome, 15 children (33%) had surgical IF but no SBS, and 10 children (22%) had functional IF. Overall, 24.3% of the children had a low BMD at the first DEXA at a median age of 6 years. Fifty percent had a low BHI at the first hand radiograph at a median age of 4.6 years. Median DEXA Z-scores and BHI Z-scores were significantly lower than reference scores, also for children already weaned off PN. There were no significant differences in BMD or BHI Z-scores between the different groups of IF. Age, duration of PN and surgical IF were related to lower Z-scores at the first DEXA. Paired DEXA and DXR results of 18 patients were compared, resulting in a Cohen’s kappa of 0.746 (‘substantial’) for BMD TB. Spearman’s correlation coefficients for BHI Z-scores and BMD TB were 0.856 (p<0.001). Hand radiography had a sensitivity of 90% and specificity of 86% (BMD TB, Table 1). Conclusion: Up to 50% of the children had a low BMD. Children with IF have a significantly poorer bone health than the reference population. Bone health assessment by DEXA and DXR showed good agreement, especially for Z-scores ≤ −2. Bone health measurement by DXR using the BoneXpert® software seems to be feasible for monitoring of bone health in children with IF.Figure