25-hydroxyvitamin D Levels and Juvenile Idiopathic Arthritis: Is there an Association with Disease Activity?

摘要

Background. The inverse association between disease activity and serum levels of 25-hydroxyvitamin D [25(OH)D] demonstrated in adults with rheumatoid arthritis has not been explored in juvenile idiopathic arthritis (JIA). The aims of this study were: to examine the association between serum levels of 25(OH)D and disease activity in JIA, to determine the prevalence of vitamin D deficiency [25(OH)D.19 ng/ml] and insufficiency [25(OH)D 20-29 ng/ml], and to determine factors associated with lower serum levels of 25(OH)D in this population. Methods. In this cross-sectional study, conducted between Oct 2009 and Sep 2010, disease activity was measured using JADAS-27 (Juvenile Arthritis Disease Activity Score 27), as well as its individual components (physician global assessment of disease activity, parent global assessment of child's well-being, count of joints with active disease, and erythrocyte sedimentation rate). Linear regression models were developed to analyze the association between serum 25(OH)D levels and JADAS-27, and to determine variables associated with serum 25(OH)D levels. Results. A total of 154 patients (61% females, 88% non-Hispanic whites) were included. Mean age was 10.6 years. Mean serum 25(OH)D level was 29.2 ng/ml. Vitamin D deficiency was detected in 13% of patients and insufficiency in 42%. JADAS-27 had a median value of 5.2 (range 0-30.7). In univariate and multivariate analyses, 25(OH)D levels were not associated with JADAS-27, nor with its individual components. However, in a subset analysis including all new onset (time since disease onset ≤ 3 months) JIA patients (n=27) there was a non-significant negative correlation between serum 25(OH)D levels and JADAS-27 (r=-0.29, p=0.14). In the univariate and multivariate analyses, age, ethnicity, BMI, and season were significantly associated with serum 25(OH)D levels, but not total vitamin D intake. Conclusions. More than one half of JIA patients had serum 25(OH)D levels below 29 ng/ml, however there was no association between serum 25(OH)D levels and disease activity in this sample of children and adolescents with JIA. Age, ethnicity, BMI, and season were associated with serum 25(OH)D levels. Future larger, long-term studies evaluating patients with new-onset JIA are needed to further explore and elucidate the association between serum 25(OH)D levels and disease activity.