Vitamin D levels in Chinese patients with systemic lupus erythematosus: relationship with disease activity, vascular risk factors and atherosclerosis

Objectives. To study the relationship of 25(OH)D-3 level with disease activity, vascular risk factors and atherosclerosis in SLE. Methods. Consecutive patients who fulfilled four or more ACR criteria for SLE were recruited for assay of 25(OH)D-3 level. Disease activity was assessed by the SLEDAI and physicians' global assessment (PGA). Patients with vascular risk factors were screened for atherosclerosis at the coronary or carotid arteries. Correlation between 25(OH)D-3 levels and SLEDAI scores was studied by linear regression. The link between vascular risk factors, atherosclerosis and vitamin D deficiency was also examined. Results. A total of 290 SLE patients were studied [94% women; mean (s.d.) age 38.9 (13.1) years; disease duration 7.7 (6.7) years; 78% patients had clinical or serological lupus activity]. Two hundred and seventy-seven (96%) patients had vitamin D insufficiency [25(OH)D-3 < 30 ng/ml] and 77 (27%) patients had vitamin D deficiency (< 15 ng/ml). Levels of 25(OH)D-3 correlated inversely with PGA (beta -0.20; P = 0.003), total SLEDAI scores (beta -0.19; P = 0.003) and subscores due to active renal, musculoskeletal and haematological disease. Subjects with vitamin D deficiency had significantly higher total/high-density lipoprotein (HDL) cholesterol ratio [3.96 (2.94) vs 3.07 (0.80); P = 0.02] and prevalence of aPLs (57 vs 39%; P = 0.007). Of 132 patients, 58 (44%) with vascular risk factors screened were positive for subclinical atherosclerosis. No association could be demonstrated between 25(OH)D-3 level and atherosclerosis, which was mainly associated with increasing age, menopause, obesity and hyper-triglyceridaemia. Conclusions. In this large cross-sectional study of SLE patients, 25(OH)D-3 level correlates inversely with disease activity. Vitamin D deficiency is associated with dyslipidaemia. In patients with vascular risk factors, subclinical atherosclerosis is not associated with hypovitaminosis D.