An investigation of vitamin D status in systemic lupus erythematosus - its relationship with disease activity, bone mineral density and quality of life

Vitamin D has the potential to modulate the immune system resulting in an inflammatory response which could lead to improved clinical outcomes for individuals diagnosed with systemic lupus erythematosus (SLE). The overall aim of this research was to investigate vitamin D status in SLE patients residing in Northern Ireland, to determine whether there was a relationship with disease activity, bone mineral density (BMD) and quality of life (QoL). To achieve this we undertook a pilot study in SLE patients (n=19) and age-and-sex matched control participants (n= 19), to investigate the vitamin D status of SLE patients. This was followed by a larger observational study to examine vitamin D status in SLE patients during winter months (November-March) and again in the summer months (June-July). A total of 52 SLE patients were recruited, of which, 50 completed the study. Serum 25-hydroxyvitamin D (25(OH)D) was assessed by liquid chromatography mass spectrometry and disease activity and damage were scored using Systemic Lupus Activity Measure (SLAM), British Isles Lupus Assessment Group (BILAG), Safety of Estrogen in Lupus Erythematosus National Assessment Trial Systemic Lupus Erythematosus Disease Activity Index (SELENA SLEDAI) and Systemic Lupus International Collaborative Clinics/American College of Rheumatology (SLICC/ ACR). BMD was measured by Dual Energy X-ray absorptiometry, fatigue was assessed by the fatigue severity score and percieved QoL was assessed using the 36-item short form health survey. BMD was measured during the winter assessment of the observational study and at both time points, associations between vitamin D, disease activity, fatigue and QoL were examined by means of correlation and regression analysis. Vitamin D inadequacy was prevalent in this cohort of SLE patients residing in Northern Ireland, although no significant difference in vitamin D status was observed between winter and summer (P=0.439). Some 98% of SLE patients presented with serum 25(OH)D concentration &lt; 75 nmol/L at both timepoints and vitamin D concentration was inversely associated with BILAG during winter. Fatigue was present in 98% of the cohort during both time points and patients with fatigue had significantly lower vitamin D status compared to those without fatigue (P=0.030). Furthermore, BILAG was a useful predictor of future fatigue in this cohort. Osteoporosis and osteopenia were identified in 8% and 45% of the SLE patients respectively, none of whom were prescribed calcium/vitamin D supplements. The social functioning (P=0.023) and mental component scores (P=0.049) of the 36-item short form questionnaire were significantly decreased during the summer. This cohort of SLE patients appeared to have much lower QoL throughout the year than that of SLE patients reported in other studies and both fatigue and disease activity were shown to be associated with QoL. The findings of this research could impact on patient care, given the high prevalence of vitamin D inadequacy and its relationship with disease activity and fatigue. These novel results provide some evidence of a potential relationship between vitamin D and disease activity. If proven, increased vitamin D status could improve clinical outcomes such as fatigue and disease activity thereby indirectly improving QoL. Future research involving vitamin D supplementation in SLE patients to optimise status would strengthen the evidence for beneficial effects of vitamin D in SLE.

Topic: Vitamin D Research Studies
Subfield: Pathology and Forensic Medicine
Field: Medicine
Domain: Health Sciences