Serum Vitamin D and Chronic Musculoskeletal Pain: A Cross-Sectional Study of 349,221 Adults in the UK.

Insufficient and deficient vitamin D may be associated with chronic musculoskeletal pain, but study findings are conflicting, and few account for important confounding factors. This cross-sectional study explored the association between serum vitamin D status and chronic musculoskeletal pain in various body sites, adjusting for a wide range and a number of potential confounding factors. Data collected at the baseline assessments of 349,221 UK Biobank participants between 2006 and 2010 were analyzed. Serum 25-hydroxyvitamin D was measured and categorized as <25.0 nmol/L (severe deficiency), 25.0 to 49.9 nmol/L (deficiency), 50.0 to 74.9 nmol/L (insufficiency), and ≥75.0 nmol/L (sufficiency). The outcome was self-reported chronic musculoskeletal pain at any site, neck/shoulder, back, hip, knee, or widespread pain that interfered with usual activities. Potential confounders were identified using directed acyclic graphs and included sociodemographic, lifestyle, psychological factors, and medical comorbidities. Simple models adjusted for age and sex showed significant associations between suboptimal vitamin D status and chronic pain across all sites (odds ratios [ORs] ranged 1.07-2.85). These associations were weakened or became insignificant after accounting for all confounding factors (ORs ≤ 1.01) for chronic regional musculoskeletal pain. Severe vitamin D deficiency remained a significant and positive association with chronic widespread pain after adjusting for all confounding factors (OR [95% confidence interval]: 1.26 [1.07, 1.49]). This study suggests that, while vitamin D status is not a key independent determinant of chronic regional musculoskeletal pain, severe vitamin D deficiency may be associated with chronic widespread pain. PERSPECTIVE: After accounting for various confounders, vitamin D deficiency was not associated with regional musculoskeletal pain. However, the relationship between chronic widespread pain severe vitamin D deficiency remained after confounder adjustment. Use of vitamin D supplements in individuals with chronic widespread pain and severe vitamin D deficiency warrants further exploration.