Severe vitamin D deficiency increases the risk for moderate to severe disease activity in Chinese patients with SLE

We aimed to investigate the prevalence of vitamin D deficiency in Chinese lupus patients and to assess the association between vitamin D levels and disease severity.

Serum levels of 25OHD3 in 121 patients with systemic lupus erythematosus (SLE) and 150 healthy controls were measured by electrochemiluminescence immunoassay. Data regarding demographics and clinical parameters were collected. Disease activity of SLE was evaluated according to the SLE Disease Activity Index (SLEDAI) score and irreversible organ damage by the Systemic Lupus International Collaborating Clinic/American College of Rheumatology, SLICC/ACR Damage Index (SDI). The multivariate logistic regression model was used to investigate the association between the degree of vitamin D deficiency and SLEDAI or SDI scores.

The prevalence of vitamin D insufficiency (25OHD3 <30 ng/ml) and severe deficiency (25OHD3 <10 ng/ml) in SLE patients was 62.81% and 34.71%, respectively. Logistic regression analysis indicated that the cut-off point of 25OHD3 concentration was 10 ng/ml where its level was correlated with increased SLEDAI (OR 6.420, p = 0.006), but not with the SDI. In addition, hydroxychloroquine treatment lowered the SLEDAI increased by the severe 25OHD3 deficiency (OR 0.280, p = 0.008). Moreover, long disease duration (OR 1.014, p = 0.008) predicted moderate to severe organ damage.

Vitamin D deficiency is highly prevalent in patients with SLE. Severe deficiency increases the risk for moderate to severe disease activity, but not for organ damage.