25-Hydroxyvitamin D deficiency is associated with increased aortic stiffness in patients with systemic lupus erythematosus

OBJECTIVE To determine the relationship between serum vitamin D and markers of subclinical cardiovascular disease (CVD) in patients with SLE. METHODS We recruited SLE patients (≥ 4 ACR 1997 criteria) from outpatient clinics between January 2007 and January 2009. Vitamin D deficiency was defined as serum 25(OH)D <20 ng/ml measured by ELISA. Disease activity was measured using the SLEDAI-2K score. Aortic pulse wave velocity (aPWV) was measured using PulseTrace 3600 (Micromedical) and carotid plaque (CP) and intima-media thickness (IMT) assessed using B-mode Doppler US. RESULTS Seventy-five women with SLE were recruited with a median (interquartile range) disease duration of 16 (8-27) years. Patients with vitamin D deficiency had higher BMI (P = 0.014) and insulin resistance (P = 0.023) than those with 25(OH)D >20 ng/ml. Subjects with SLEDAI-2K ≥ 4 had lower 25(OH)D than those with SLEDAI-2K <4 (median 12.9 vs 20.3 ng/ml, P = 0.031). Aortic stiffness was significantly associated with serum 25(OH)D [log(aPWV) β (95% CI) -0.0217 (-0.038, -0.005), P = 0.010] independently of BMI, CVD risk factors and serum insulin. Adjustment for disease activity reduced the strength of the association. There was no association between 25(OH)D and CP or IMT. CONCLUSIONS Vitamin D deficiency is associated with increased aortic stiffness in SLE, independent of CVD risk factors and insulin. Increased inflammatory disease activity may be the mechanism by which vitamin D deficiency mediates vascular stiffness in this patient group.