Low bone mineral density in Thai children with systemic lupus erythematosus: prevalence and risk factors

Abstract

Background Improvement of disease recognition and management has increased the survival of children with systemic lupus erythematosus (SLE), but has shifted the morbidity focus toward long-term complications, such as low bone mass and osteoporosis. Studies in adults with SLE show older age, chronic inflammation, and corticosteroid therapy are risk factors for low bone mineral density (BMD) and osteoporosis. Objectives To determine the prevalence of and identify risk factors associated with low BMD in Thai children with SLE. Methods We conducted a retrospective review of demographic data and clinical variables for a cohort of 60 Thai children with SLE who underwent 2 dual-energy X-ray absorptiometry (DXA) at their initial examination and later follow-up. We considered a BMD z score ≤ −2.0 to indicate low BMD. Binary logistic regression was used to assess risk factors potentially associated with low BMD. Results The prevalence of low BMD at the first visit was 40% and increased to 55% over follow-up. We found a significantly decreased hip BMD z score (median difference −0.25, 95% confidence interval [CI] −0.40 to −0.05; P = 0.016) and lumbar BMD z score (median difference −0.49, 95% CI −0.69 to −0.28; P < 0.001) over time. The cumulative steroid dose tended to be higher for patients with low BMD (adjusted odds ratio [OR] = 1.08, 95% CI 1.00 to 1.17; P = 0.050). Conclusion Low BMD has a 40% prevalence in Thai children newly diagnosed with SLE and progresses significantly over time. Higher cumulative corticosteroid dose tended to be associated with a low BMD, but we did not find a significant risk in this small sample.