Combined Effects of Physiotherapy and Vitamin D Supplementation on Pain, Disability, and IL-6 Expression in Chronic Low Back Pain: A Randomized Controlled Trial

Background: Chronic low back pain (CLBP) is a leading cause of global disability, linked to elevated IL-6 and vitamin D deficiency or insufficiency. While interferential current (IFC) therapy and exercise therapy are established treatments, their combined effect with vitamin D supplementation on inflammatory biomarkers, pain, and functional disability remains underexplored. Objective: The aim of this study was to evaluate the combined effects of physiotherapy and vitamin D supplementation on pain, disability, IL-6 expression, and vitamin D levels in CLBP patients. Methods: This two-arm, parallel-group, randomized controlled trial enrolled 60 CLBP patients, randomized into Group A (physiotherapy alone: IFC therapy and exercise therapy; n = 30) or Group B (physiotherapy plus vitamin D supplementation; n = 30). Outcomes included pain intensity (11-point Numeric Pain Rating Scale (NPRS)), disability (Arabic Oswestry Disability Index (ODI), 0–100%), and serum IL-6 and 25-hydroxyvitamin D (both by ELISA; pg/mL and ng/mL, respectively), which were assessed at baseline and 6 weeks. All 60 participants enrolled had laboratory-confirmed vitamin D deficiency or insufficiency (serum 25(OH)D < 20 ng/mL) at screening. Independent samples t-tests compared continuous baseline characteristics and between-group differences in 6-week change scores; paired t-tests assessed within-group change from baseline to 6 weeks; the chi-square test compared the categorical variable of gender (α = 0.05). Results: Both groups showed significant improvements in NPRS and ODI at six weeks (p < 0.001). Group B demonstrated significant reductions in NPRS (−3.01 vs. −1.71) and ODI (21.83% vs. 16.33%). IL-6 decreased significantly only in Group B (18.24 pg/mL, p < 0.001), with no significant change in Group A (25.96 pg/mL, p = 0.626). Vitamin D levels increased significantly in Group B (31.68 ng/mL, p < 0.001) compared with Group A (19.68 ng/mL, p = 0.115), a between-group difference that was also statistically significant. Conclusions: Combining physiotherapy with vitamin D supplementation improves outcomes in the management of CLBP. This approach effectively reduces pain, functional disability, inflammation, and vitamin D deficiency or insufficiency, offering a comprehensive, evidence-based treatment strategy.