Background Vitamin D (25(OH)D) deficiency seems a distinct risk factor influencing prevalence and severity of several autoimmune diseases. Several studies suggest that low serum concentrations of vitamin D are frequent in rheumatoid arthritis (RA) patients, and an inverse relationships have been reported between 25(OH)D serum concentrations and disease activity or disability.
Objectives European multicentre cross-sectional study to collect data on vitamin D serum concentrations in RA patients from different countries, and to investigate the relationship with disease activity, disability and quality of life in a large population.
Methods The survey involved 625 RA patients (mean age 55±11 years, mean disease duration 11±9 years) and 276 age and sex-matched healthy subjects from 13 European countries. Serum samples for 25(OH)D measurement were collected during winter time (December-March) and analyzed in a central laboratory using chemiluminescence immunoassay (DiaSorin). Thirty-six percent of RA patients were treated with vitamin D analogues. Patient past medical history, Rheumatoid Arthritis Impact Diseases (RAID) score, Health Assessment Questionnaire (HAQ) and DAS28-CRP were also collected. Statistical analysis was performed by non parametric tests.
Results Mean serum concentration of 25(OH)D was found significantly lower in RA patients (17.6±9.7 ng/ml) when compared to matched controls (18.9±9.4 ng/ml) (p=0.01), Several statistically significant differences between European countries were observed (possibly linked to different latitude, sun exsposure and dietary habits) (see figure). Vitamin D deficiency (<20 ng/ml) was found in almost 66% of RA patients, and severe deficiency (<10 ng/ml) was detected in almost 25% of them; insufficiency (between 20 and 30 ng/ml) was found in 27% of RA patients. Only 6% of the RA patients were found within the normal concentrations (>30 ng/ml). Male and female RA patients showed similar 25(OH)D values. Negative statistically significant correlations were found between 25(OH)D serum concentrations and RAID (p=0.05) HAQ (p=0.04) and DAS28-CRP (p<0.001) scores in the RA patients group.
Conclusions This European survey add new evidences that vitamin D insufficiency/deficiency is frequent in RA patients with statistically significant differences between several countries. Vitamin D serum concentrations negatively correlate with the clinimetric indexes for disease activity, disability and quality of life in the present cohort of RA European patients.
Disclosure of Interest None declared