THU0584 Vitamin d status in patients with juvenile idiopathic arthritis and its association with disease activity and progression – results from the inception cohort icon
Authors: C. Sengler, J. Zink, J. Klotsche, D. Foell, M. Niewerth, I. Liedmann, G. Horneff, J.-P. Haas, K. Moenkemoeller, A. Thon, K. Minden
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Vitamin D has been shown to have immunomodulatory properties in addition to its well-established role in the maintenance of mineral homeostasis and bone health. Conflicting data have been available regarding vitamin D status in children and adolescents with juvenile idiopathic arthritis (JIA) and its influence on the disease. <h3>Objectives</h3> To determine 25–0 hour-vitamin D3 (25-OHD) levels in patients with JIA, and to evaluate whether 25-OHD levels are associated with disease activity and disease course. <h3>Methods</h3> Serum 25-OHD levels were determined in a pair of serum samples from patients with JIA who were enrolled in the JIA inception cohort study ICON and prospectively followed for three years. The frequencies of 25-OHD deficiency (defined as &lt;20 ng/ml) and 25-OHD sufficiency (≥30 ng/ml) were determined and compared with those of the age-, sex- and ethnicity-matched general population (KIGGS study). The association of 25-OHD levels and the likelihood for uveitis were analysed by a Cox-proportional hazard model. Logistic regression analysis was used to investigate the predictive value of 25-OHD in terms of disease progression into extended oligoarthritis (OA). <h3>Results</h3> In 360 patients with early JIA (48% OA, 27% rheumatoid-factor negative polyarthritis), 25-OHD levels were determined twice: after a median disease duration of 6.6 and of 13.0 months. The mean 25-OHD level of all JIA samples was insufficient (22.1 ng/ml, SD 7.8), but significantly higher than that of the control population (18.4 ng/ml, SD 10, p&lt;0.001). Vitamin D levels decreased with age in patients and controls, but did not differ between males and females. An insufficient mean 25-OHD level was found in 40% of JIA patients and in 25% in both samples each, sufficient levels in 13% and 7%, respectively. There were no significant differences in 25-OHD levels among the JIA categories. Disease activity, measured by the cJADAS-10, was inversely correlated with the first 25-OHD level (β=−0.20, 95% CI −0.37,–0.03, p=0.018), especially in 141 DMARD-naïve patients (β=−0.26, 95% CI −0.44,–0.01, p=0.041). Up to the 3-year-follow-up, 17% (61/360) developed uveitis, and 30% (52/173) of OA patients an extended OA. While 20% (17/87) of those with 25-OHD deficiency at both measurements were affected by uveitis, this applied to only 9% (2/23) in those with sufficient levels. Multivariable regression analysis revealed that the 25-OHD level was significantly associated with the risk to develop uveitis (Hazard ratio 0.95, 95% CI 0.91,0.99, p=0.008). Twelve out of 29 (41%) patients with OA and two deficient vitamin D levels, but only 2 of 14 (14%) with two sufficient 25-OHD levels developed extended OA during the first 3 years (p=0.034). <h3>Conclusions</h3> Overall, vitamin D levels were higher in JIA patients than in matched controls. JIA patients with higher disease activity had lower 25-OHD levels. In particular, complicated courses with uveitis or the development of polyarthritis seem to be associated with lower 25-OHD levels. Further studies are needed to substantiate these results. <h3>Acknowledgements</h3> ICON is funded by the Federal Ministry of Research (FKZ:01ER0812) <h3>Disclosure of Interest</h3> C. Sengler: None declared, J. Zink: None declared, J. Klotsche: None declared, D. Foell: None declared, M. Niewerth: None declared, I. Liedmann: None declared, G. Horneff Grant/research support from: Abbvie, Pfizer, Roche, Chugai, MSD, J.-P. Haas: None declared, K. Moenkemoeller: None declared, A. Thon: None declared, K. Minden Grant/research support from: Pfizer, Abbvie, Roche