Research presented at the European League Against Rheumatism Annual European Congress of Rheumatology found that vitamin D deficiency was linked to fatigue and symptom severity in patients with fibromyalgia.  Fibromyalgia is a disorder characterized by widespread musculoskeletal pain, fatigue, sleep, memory and mood disturbances. The onset of fibromyalgia often occurs after physical trauma, surgery, infection or severe psychological stress. However, symptoms can gradually develop over time without a triggering event.  Prior studies have shown a high prevalence of vitamin D deficiency among patients with fibromyalgia.

In the study, researchers wanted to determine the relationship between vitamin D blood levels and fibromyalgia. They compared symptom severity between three different patient groups: patients with fibromyalgia and vitamin D sufficiency, patients with fibromyalgia and vitamin D deficiency, and patients with vitamin D deficiency. All patients enrolled into the study were women.  Researchers assessed the severity of fibromyalgia and its symptoms using the Bath Ankylosing Spondylitis Functional Index (BASFI), Health Assessment Questionnaire (HAQ), Widespread Pain Index (WPI) and Symptom Severity Score (SSS). A high BASFI score indicates a high degree of functional limitation. The HAQ assesses disability with a high score indicating increased disability. 

The researchers found that fatigue was significantly higher among patients with both fibromyalgia and vitamin D deficiency than in the other two groups. Additionally, BASFI and HAQ scores were higher in patients with fibromyalgia and vitamin D deficiency. WPI and SSS scores were only marginally higher in patients with fibromyalgia and vitamin D deficiency compared to patients with fibromyalgia.