Association of low vitamin d with high disease activity in an australian systemic lupus erythematosus cohort.

Abstract

Background/Purpose: Previous cross-sectional studies suggest that low vitamin D may be associated with higher disease activity in SLE. Vitamin D status varies with geographic location and no studies have been reported in the Southern hemisphere. The aim of this study was to determine the relationship between Vitamin D and disease activity in SLE patients in an Australian centre. Method(s): Data was collected prospectively on patients with SLE (>4 criteria) in the Monash Lupus Clinic in Melbourne Australia between January 1 2008 and January 1 2011 who had disease activity (SLEDAI-2k) and serum 25-hydroxyvitamin D concentration (VD25) measured at the same visit. Where multiple values were available, the assessment with lowest VD25 was used (n=119). Result(s): Patients with VD25 in the lowest quartile had significantly higher SLEDAI (7.7+/-1.3) compared to those in the highest quartile (3.9+/-0.8, p=0.014). Accordingly, VD25 deficiency (VD25>=40, n=28) was associated with significantly increased SLEDAI (7.7+/-1.3) compared to patients with VD25 >40 (4.8+/-0.6, P=0.02). The relative risk of high disease activity (SLEDAI>8) for patients with VD25 deficiency was 1.6 (95% CI 1.1-2.2, P=0.002). In parallel, high disease activity was associated with significantly lower VD25 compared to patients with SLEDAI<8 (P= 0.048) or patients with inactive disease (SLEDAI<4, P=0.0073). When assessing all values, a significant negative correlation between SLEDAI and VD25 was observed (Spearman r =0.2, p =0.03). There was no association of VD25 with corticosteroid use, SLICC SLE Damage Index (SDI), or ethnicity.Vitamin D supplement use (n=53) was significantly more common among patients using corticosteroids (P=0.0001) and was associated with significantly higher VD25 (P=0.009). However, there was no association between Vitamin D supplementation and SLEDAI. Conclusion(s): In a cohort of Australian patients with SLE, Vitamin D correlates negatively with disease activity. Prospective studies should examine the predictive value of Vitamin D levels and therapeutic effect of Vitamin D.