Vitamin D concentrations and disease activity in Moroccan children with juvenile idiopathic arthritis

BACKGROUND In addition to its important metabolic activities, vitamin D also contributes to the regulation of the immune system. The aim of this study was to assess the relationship between hypovitaminosis D and disease activity in Moroccan children with juvenile idiopathic arthritis (JIA). METHODS In this cross-sectional study, forty children with JIA were included, all having been diagnosed according to the classification criteria of International League of Associations for Rheumatology (ILAR). The children underwent anthropometric assessment and clinical evaluation. Disease activity was measured using the Disease Activity Score in 28 joints (DAS28) for polyarticular and oligoarticular JIA and the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) for enthesitis-related arthritis. Serum 25-hydroxyvitamin [25(OH)D] D2 and D3 were measured using radioimmunoassay (RIA). Hypovitaminosis D was defined as serum 25(OH)D <30 ng/ml. RESULTS The average age of participants was 11 years ± 4.23. Hypovitaminosis D was observed in 75% of patients. In univariate analyses, 25(OH)D levels were negatively associated with DAS28 for polyarticular and oligoarticular JIA. No significant relationship was found between 25(OH)D levels and BASDAI for juvenile spondylarthropathy. In multivariate linear regression analysis, no association persisted between 25(OH)D levels and DAS28. CONCLUSIONS Our study suggested that serum levels of vitamin D were low in Moroccan children with JIA disease. Future studies with a larger population are needed to confirm our results.