Background Low vitamin D level has been linked to cardiovascular diseases and mortality in the general population. Hypovitaminosis D is associated with certain traditional vascular risk factors in patients with SLE.

Objectives To study the relationship between the metabolic syndrome (MetS) and serum 25-hydroxyvitamin D level in patients with SLE

Methods Consecutive patients who fulfilled >=4 ACRcriteria for SLEin a two-month period were recruited from our out-patient lupus clinics. Blood was taken in the morning for the assay of 25-hydroxyvitamin D3 (enzyme immunoassay; Immunodiagnostic Systems Inc, Fountain Hills, AZ, USA) and high sensitivity C-reactive protein (hsCRP) (solid phase chemilluminescence immunometric assay; Siemens Healthcare Diagnostics, Deerfield, Il., USA). Clinical assessments (waist circumference, fasting glucose and lipid level, blood pressure) were made for each patient who was stratified for the MetS according to the 2009 International joint consensus criteria, using the Asian criteria for abdominal obesity(ref 1). The relationship between 25-hydroxyvitamin D level and the MetS was studied by linear regression, with adjustment for other confounding covariates.

Results 257 SLE patients (94% women) were studied. All were ethnic Chinese. The mean age was 39.6±13.1 years and SLE duration was 8.3±6.9 years. Vitamin D insufficiency (25-hydroxyvitamin D3 <30ng/mL), deficiency (25-hydroxyvitamin D3 <15ng/mL, and severe deficiency (level<10ng/mL) was present in 95%, 25% and 3.5% of patients, respectively. The prevalence of the MetS was 8.3%, 11% and 22.2% in patients with vitamin D insufficiency, deficiency and severe deficiency, respectively. None of the patients with 25-hydroxyvitamin D3 levels >30ng/mL fulfilled the criteria for the MetS. Linear regression analysis revealed that levels of 25(OH)vitamin D3 were independently associated with age (Beta 0.19; p=0.002), the presence of the MetS (Beta -0.14; p=0.049) and hsCRP level (Beta -0.14; p=0.04) after adjustment for gender, SLE duration, duration of sunshine in the month of venepuncture, SLE damage scores (SDI), smoking ³3 years, renal insufficiency (estimated CrCl < 50ml/min), photosensitivity and ever use of glucocorticoids.

Conclusions Vitamin D deficiency is prevalent in patients with SLE. Hypovitaminosis D is independently associated with the MetS and hsCRP, suggesting that it is a novel risk factor for vascular thrombosis in patients with SLE.

References

1. Alberti KG et al. Circulation 2009;120:1640–5.

Disclosure of Interest None Declared