Vitamin D status in ANCA-associated vasculitis.

Objective Vitamin D might participate in the pathogenesis of several immune-mediated diseases, but few related data are available for ANCA-associated vasculitis (AAV). In this study, we analysed the association between vitamin D status and disease in patients with AAV. Methods Serum levels of 25(OH)D_2/3 were measured in 125 randomly selected patients with AAV [granulomatosis with polyangiitis (n  = 50), eosinophilic granulomatosis with polyangiitis (n  = 50) or microscopic polyangiitis (n  = 25)] enrolled in the Vasculitis Clinical Research Consortium Longitudinal Studies at the time of enrolment and a subsequent relapse visit. Sufficient, insufficient and deficient vitamin D status were defined as 25(OH)D₃ levels >30, 20–30 and ˂20 ng/ml, respectively. Results Seventy of 125 patients (56%) were female, with a mean age of 51.5 (16) years at diagnosis; 84 (67%) were ANCA positive. Mean 25(OH)D was 37.6 (16) ng/ml, with vitamin D deficiency in 13 (10.4%) and insufficiency in 26 (20.8%). In univariate analysis, lower vitamin D status was associated with male sex (P  = 0.027) and disease activity (P  = 0.047). In univariate and multivariate analyses, deficient vitamin D status was associated with disease activity (P  = 0.015). Mean 25(OH)D status in the 21 patients with a subsequent relapse did not differ between baseline and relapse visit [37.8 (16) vs 38.0 (10) ng/ml, respectively; P  = 0.92]. Conclusion Most patients with AAV have sufficient 25(OH)D levels, although those with lower vitamin D status were more likely to be male and to have active disease. Whether optimization of vitamin D status alters disease manifestations or activity in AAV remains to be determined. Trial Registration Vasculitis Clinical Research Consortium (VCRC) Longitudinal Study (LS), NCT00315380, https://clinicaltrials.gov/ct2/show/NCT00315380 [ABSTRACT FROM AUTHOR]