ESPE Abstracts

Introduction: Osteoporosis is well described among children with rheumatological conditions. Data on the specific bone deficits and microarchitectural alterations in this group of children are limited. This study aimed to assess the bone microarchitectural alterations in children with rheumatological conditions on long-term glucocorticoids using high-resolution peripheral quantitative computed tomography (HR-pQCT).

Methods: This was a cross-sectional, case-control study. Children with rheumatological conditions on long-term glucocorticoids (>4 weeks) and with no prior history of clinically significant fracture were recruited from a single quaternary centre for comprehensive bone health assessment, including areal bone mineral density (aBMD) assessment and vertebral fracture assessment (VFA) by dual x-ray absorptiometry (DXA), measurement of Bone Health Index (BHI) by BoneXpert (a function of cortical thickness of three central metacarpals and their width and length), volumetric BMD and bone microarchitecture assessment at the non-dominant distal radius using HR-pQCT. For each recruited patient, one gender- and age-matched control were selected randomly from an existing HR-pQCT database of healthy individuals.

Results: Twenty-eight patients were included in the study (girls = 16). Their median age was 14.1 years (IQR: 11.8 to 16.8 years) and their median duration of illness was 1.7 years (IQR: 0.8 to 3.4 years). At the time of assessment, the median prednisolone dose was 0.12 mg/kg/day (IQR: 0.1 to 0.2 mg/kg/day). The mean 25(OH) vitamin D level was at 67.0 +/- 37.6 nmol/L. Their median DXA aBMD height-adjusted Z-scores (HAZ) at LS and TBLH were -0.9 SD (IQR: -1.4 to -0.1 SD) and −1.9 SD (IQR – 3.0 to – 1.3 SD), respectively. The median BHI was -1.2 SD (IQR -2.5 to -0.6 SD). The HR-pQCT findings of these 28 patients were compared with 28 gender- and age-matched healthy controls. Trabecular microstructure indices, including trabecular volumetric BMD and number of trabeculae, were significantly lower, while cortical vBMD and cortical thickness were significantly higher in children with rheumatological conditions when compared to the healthy controls (P < 0.05).

Conclusion: Lower microarchitectural measurement of trabecular bones, but higher cortical vBMD, were observed in children with rheumatological conditions on long-term oral glucocorticoids. The results from this study provide preliminary, yet valuable perception on the bone microarchitectural alterations in this group of patients.