Effect of vitamin D on widespread pain index of fibromyalgia patients

Various studies have reported hypovitaminosis D in Fibromyalgia patients. In the present study, we have evaluated the effect of vitamin D supplements on widespread pain index of fibromyalgia patients. The present study was performed from October 2012 to February 2014 in Rheumatology Clinic of Firoozgar Hospital. A total of 74 patients diagnosed as fibromyalgia according to American College of Rheumatology (ACR 2010) criteria who had hypovitaminosis D were selected. Patients were randomized to two groups. Group A received oral vitamin D 50000IU weekly plus trazodone 25 mg at bedtime and group B received trazodone 25 mg at bedtime only.The patients were evaluated at baseline and 4 and 8 weeks post treatment. At each visit physical examination for tender points and 25 (OH) D level measurement were performed. About 68.5% of patients with fibromyalgia had hypovitaminosis D. The mean 25(OH) D was 12.4±6.9 ng/ml (11.4±6.5 ng/ml and 13.4±7.3 ng/ml in group A and group B, respectively). There was no significant difference between the two groups at baseline. Comparison between widespread pain index (WPI) scores before and after treatment showed a significant improvement in both groups, 12.2±2.4 at baseline to 4.5±2.5 at week 8 in group A vs. 13.5±3.4 to 8±4.8 in group B. Patients receiving vitamin D showed more improvement than those receiving trazodone only, mean WPI score differences of 7.8±2.8 vs. 5.5±4 respectively, p=0.007. The present study indicated that treating hypovitaminosis D may improve WPI in Fibromyalgia patients.