Background 25-hydroxy-vitamin D [25(OH) D] insufficiency/deficiency has been associated with many chronic diseases. There are only a few studies in the literature that have analyzed vitamin D status in juvenile idiopathic arthritis (JIA).
Objectives Our purpose was to assess the prevalence and associations of 25(OH) D insufficiency/deficiency in children’s and adults with JIA.
Methods We have recruited 40 patients with JIA according to the criteria of the International League of Associations for Rheumatology (ILAR). Age, gender, disease duration, radiological joint destructive changes and medical treatments were collected. Questionnaires were performed to evaluate mean sun exposure time and dietary intake of vitamin D. In all we evaluated the current Disease Activity Score for 28 joints (DAS 28).
From November 2011 until January 2012, blood samples were drawn in all patients, and phosphorus, calcium, alkaline phosphatase, ESR, CRP and serum 25(OH) D levels were measured. Serum levels between 20-30 ng/ml were classified as vitamin D insufficiency and levels <20 ng/ml as vitamin D deficiency. None of the patients were receiving vitamin D supplementation at the time of or during the year prior to study entry.
In the statistical analysis (chi-Square and student T-test for categorical and continuous variables, respectively), a significant association was considered if p<0.05.
Results We have evaluated 31 females and 9 males, with a mean age of 22.3 (4-63 years) and disease duration of 14.6±12.1. Regarding the dietary intake, we found that 32.5% had high intake of vitamin D and 27.5% had normal values, while 40% had insufficient intake. The mean sun exposure time throughout the last year was 77.4 minutes/day. The blood levels of calcium, phosphorus and alkaline phosphatase were normal in all patients.
We found low levels of vitamin D in 75% of patients:the prevalence of 25(OH) D insufficiency and deficiency were 47.5% and 27.5%, respectively. JIA patients with less sun exposure and higher ESR had significantly lower vitamin D levels. We also found that patients who had greater joint destruction had lower levels of vitamin D, although not statistically significant (p=0.07). There was no association between vitamin D levels and gender, disease duration, intake of vitamin D, CRP, therapy with corticosteroids, number of DMARDs and biological agents per patient or the current DAS28.
Conclusions Our study demonstrated that the prevalence of vitamin D deficiency/insufficiency among JIA patients is very high. Although there is a tendency for patients with more joint destruction to present lower levels of vitamin D, sun exposure and ESR seem to be the most important factors. A limitation of this study was the fact that it was performed during winter, when sun daily availability is lower. Future larger, long-term studies evaluating patients with JIA are needed to further elucidate the association between serum 25(OH)D levels and disease activity.
Disclosure of Interest None Declared
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