Association Between Vitamin D Deficiency and Chronic Musculoskeletal Pain Among Adults: An Analytical Study

Background: Vitamin D deficiency has emerged as a clinically significant contributor to chronic musculoskeletal pain, functional limitation, and impaired rehabilitation outcomes. Low serum 25-hydroxyvitamin D [25(OH)D] levels may influence pain sensitization, skeletal muscle function, and inflammatory pathways, yet evidence regarding its association with persistent musculoskeletal symptoms remains inconsistent across populations. Objective: To determine the association between vitamin D deficiency and chronic musculoskeletal pain among adults and to identify predictors of poor clinical outcome in patients presenting to rehabilitation and orthopedic services at Riphah International University, Lahore, Pakistan. Methods: A hospital-based analytical observational study was conducted among 178 adults with chronic musculoskeletal pain. Demographic, clinical, and laboratory data were collected using structured assessment protocols. Pain severity was evaluated using the Visual Analog Scale (VAS), while serum 25(OH)D levels were measured using standardized biochemical methods. Vitamin D deficiency was defined as serum 25(OH)D <20 ng/mL and severe deficiency as ≤10 ng/mL. Logistic regression analysis was used to identify predictors of poor clinical outcome. Results: Vitamin D deficiency was identified in 57.9% of participants, while severe deficiency was present in 17.4%. Mean baseline VAS pain score was 6.7 ± 1.9. Poor clinical outcome occurred in 35.4% of participants. Vitamin D deficiency independently predicted poor outcome (OR 2.41, 95% CI: 1.31–4.46, p = 0.004), while severe deficiency markedly increased risk (OR 3.18, 95% CI: 1.42–7.11, p = 0.002). Low sunlight exposure, sedentary lifestyle, obesity, chronic widespread pain, and higher baseline pain severity were also significant predictors. Improvement in serum vitamin D levels was associated with reduced odds of persistent symptoms (OR 0.69, 95% CI: 0.52–0.88, p = 0.005). Conclusion: Vitamin D deficiency was significantly associated with chronic musculoskeletal pain, functional limitation, and poor recovery outcomes. Incorporating vitamin D assessment and lifestyle-based interventions into rehabilitation and musculoskeletal care may improve clinical recovery and functional outcomes in affected adults.