Vitamin D insufficiency in Brazilian patients with SLE: prevalence, associated factors, and relationship with activity

The influence of vitamin D on the severity of systemic lupus erythematosus (SLE) has been studied. Our objectives were to determine the prevalence of vitamin D insufficiency in Brazilian lupus patients and its relationship with demographic, clinical, and laboratory variables and to study the relationship between vitamin D insufficiency and disease activity. This is a cross-sectional study of 159 SLE patients. Levels of serum 25-hydroxyvitamin D (25(OH) D) < 30 ng/ml were defined as vitamin D insufficiency and < 20 ng/ml as deficiency. Data collected included sex, age, ethnicity, postmenopausal status, disease duration, cumulative amount of oral glucocorticoids (GC) in the last six months, duration of GC usage, calcium and vitamin D supplements, photosensitivity, sunscreen usage, sun exposure, diabetes mellitus, creatinine clearance, lifestyle habits, and smoking. Disease activity was measured by the SLE Disease Activity Index 2000 (SLEDAI-2K). Bivariate statistical analysis was performed using the Mann-Whitney test, Spearman's correlation coefficient, Chi-square test, and Fisher's exact test. Multivariate analysis was performed with multiple linear regression. The prevalence of vitamin D insufficiency and deficiency were 37.7% and 8.2%, respectively. Levels of 25(OH) D were not associated with lupus activity score, disease duration, sun exposure, vitamin D supplementation, or use of corticosteroids. Lupus (2011) 20, 1019-1026.