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)D3 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)D3 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)D3 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)D3 < 30 ng/ml] and 77 (27%) patients had vitamin D deficiency (<15 ng/ml). Levels of 25(OH)D3 correlated inversely with PGA (β −0.20; P = 0.003), total SLEDAI scores (β −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)D3 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)D3 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.