Association between serum 25-hydroxyvitamin D₃ concentrations and disease activity in rheumatoid arthritis: A cross-sectional study

Objective: To investigate the association between serum 25-hydroxyvitamin D₃ [25(OH)D₃] concentrations and disease activity inpatients with rheumatoid arthritis (RA).Patients and Methods:This cross-sectional study included 200 adults with RA and 77 healthy controls. Serum 25(OH)D₃ concentrationswere measured by electrochemiluminescence immunoassay. Vitamin D status was classified as deficiency, insufficiency, or sufficiency.Disease activity was assessed using the Disease Activity Score in 28 joints based on erythrocyte sedimentation rate (DAS28-ESR).Associations were evaluated using correlation and multivariable regression analyses.Results: Serum 25(OH)D₃ concentrations were significantly lower in patients with RA than in controls (20.2 ± 18.3 vs. 60.3 ± 25.5ng/mL, p