Incident vertebral fractures among children with rheumatic disorders 12 months after glucocorticoid initiation: a national observational study

Abstract

Objective: To determine the frequency of incident vertebral fractures (IVF) 12 months after glucocorticoid (GC) initiation in children with rheumatic diseases and to identify children at higher risk.

Methods: Children with rheumatic diseases initiating GC were enrolled in a prospective observational study. Annual spine radiographs were evaluated using the Genant semiquantitative method. Spine areal bone mineral density (aBMD) was measured every 6 months. Clinical features, including cumulative GC dose, back pain, disease and physical activity, calcium and vitamin D intake, and spine aBMD Z scores, were analyzed for association with IVF.

Results: Seven (6%) of 118 children (95% confidence interval 2.9-11.7%) had IVF. Their diagnoses were: juvenile dermatomyositis (n = 2), systemic lupus erythematosus (n = 3), systemic vasculitis (n = 1), and mixed connective tissue disease (n = 1). One child was omitted from the analyses after 4 months because of osteoporosis treatment for symptomatic IVF. Children with IVF received on average 50% more GC than those without (P = 0.030), had a greater increase in body mass index (BMI) at 6 months (P = 0.010), and had greater decrements in spine aBMD Z scores in the first 6 months (P = 0.048). Four (67%) of 6 children with IVF and data to 12 months had spine aBMD Z scores less than -2.0 at 12 months compared to 16% of children without IVF (P = 0.011).

Conclusion: The incidence of VF 12 months following GC initiation was 6%; most children were asymptomatic. Children with IVF received more GC, had greater increases in BMI, and had greater declines in spine aBMD Z scores in the first 6 months.

Figure 1

Mean z-scores for height, weight, body mass index (BMI) and lumbar spine (LS) areal bone mineral density (aBMD) Z-scores at study entry and 12 months.

Figure 2

Examples of incident vertebral fractures at 12 months. A (I) shows a normal spine radiograph at study entry (within 30 days of glucocorticoid initiation) in an 11 year old girl with systemic lupus erythematosus. At 12 months (II), this child manifested a grade 1 incident vertebral fracture at L1. B (I) shows a normal spine radiograph at study entry in a 16 year old girl with systemic lupus erythematosus. At 12 months (II), this child was identified as having a grade 2 incident vertebral fracture at T11.

Figure 3

Spine radiographs from a 7 year old girl with mixed connective tissue disease. At study entry (A), her spine radiograph showed no signs of vertebral fractures; however, she manifested multiple, painful vertebral fractures during the observation period (B). This patient was excluded from the bone health natural history analyses because she required bisphosphonate therapy to treat the symptomatic fractures; however, a brief description of her skeletal phenotype is provided in the Results.