Background Fibromyalgia (FM) is a condition characterized by chronic widespread musculoskeletal pain (MSK), fatigue and muscle tenderness. In addition, many patients have mood disturbances, report fatigue, disrupted sleep, balance disorders and decreased muscle strength. Reduced vitamin D levels are implicated in the pathogenesis of diffuse musculoskeletal pain in FM patients. A possible association between chronic widespread pain of FM and vitamin D deficiency has thus been suggested.

Objectives To evaluate the efficacy of vitamin D supplementation in the treatment of FM.

Methods Seventy-two consecutive FM patients diagnosed according to the American College of Rheumatology (ACR) 2010 criteria for FM were randomized into 2 groups, the first group (n=36) received oral cholecalciferol 2000 IU/day and the second group (n=36) received placebo for 6 months. Outcome measures included the Fibromyalgia Impact Questionnaire (FIQ), Brief Pain Inventory (BPI), Beck Depression Inventory (BDI), Visual analogue scale for pain (VAS 0-100mm) and Survey Short Form-36 (SF-36) assessment. Vitamin D levels were measured by Liaison immunoassay (normal 30–100 ng/ml). Serum levels between 10 and 30 ng/ml were classified as vitamin D insufficiency and levels <10 ng/ml as vitamin D deficiency. All measures were assessed at baseline and after 6 months. Safety and tolerability were also assessed.

Results The mean 25(OH) D level at baseline was 19.9 ng/ml in patients compared to 28.5 ng/ml in controls. The overall prevalence of suboptimal and deficient 25(OH) D serum levels among patients with FM at baseline was 50/72 (69%) and 27/72 (38%), respectively. There was a statistically significant reduction in pain as shown by VAS scores in the intervention group compared to the placebo group (6.6±2.5 vs 2.9±2.7, p<0.001) at 6 months. Furthermore, there was a significant improvement in physical function (SF-36 and FIQ) scores. Lower 25(OH) D levels correlated significantly with higher FIQ scores, r =0.549; p<0.005). A statistically significant between-group difference was observed for depression as assessed by BDI. Optimization of vitamin D levels in FM had a positive effect on the pain perception.

Conclusions Vitamin D may be an effective, cheap and useful addition to the therapeutic armamentarium for fibromyalgia. However, larger, long-term studies are required to confirm the results of the present study.

Disclosure of Interest : None declared

DOI 10.1136/annrheumdis-2014-eular.2767