Serum Interleukin-8 Levels and Their Association with Anxiety and Functional Disability in Military Personnel with Chronic Low Back Pain

Background/Objectives: Chronic low back pain (LBP) remains a leading cause of disability and healthcare utilization globally, with complex, multifactorial pathophysiology. Despite advances in imaging, diagnosis often remains challenging due to poor correlation between structural findings and clinical symptoms. Recent evidence suggests inflammatory mechanisms may underlie persistent pain. This study investigated whether systemic inflammatory cytokines are altered in military personnel with chronic LBP and examined their relationships with clinical manifestations, psychological factors, and radiological findings. Methods: In this cross-sectional study, we enrolled 50 patients with chronic non-specific LBP (duration ≥ 3 months) and 50 age-, sex-, and BMI-matched healthy controls. All patients underwent a comprehensive clinical assessment, which included evaluation of pain intensity (VAS), neuropathic pain screening (DN4), psychological assessment (HADS), fibromyalgia screening (FIRST), and assessment of functional disability (Oswestry Disability Index and Roland-Morris Disability Questionnaire, EIFEL). Serum levels of IL-6, IL-8, IL-1β, TNF-α, and IL-10 were measured using chemiluminescence and enzyme-linked immunosorbent assay (ELISA) techniques. Radiological findings were documented through MRI and CT imaging of the lumbar spine. Results: Serum IL-8 levels were significantly elevated in patients with chronic LBP compared to healthy controls (8.52 ± 6.7 vs. 4.8 ± 0.56 pg/mL, p < 0.001). Weak positive correlations were observed between IL-8 levels and anxiety scores (r = 0.3, p = 0.02) and functional disability, as measured by the EIFEL questionnaire (r = 0.3, p = 0.04); however, these associations did not remain significant after Bonferroni correction for multiple testing. Similarly, IL-6 showed a weak positive correlation with BMI (r = 0.21, p = 0.03) and a weak negative correlation with lumbar mobility, as assessed by Schober’s test (r = −0.38, p = 0.03), which also did not survive correction for multiple comparisons. Conclusions: This study identified serum IL-8 as a potential biomarker for chronic LBP. While we observed associations between specific inflammatory markers and psychological distress and functional disability, these correlations were weak and did not remain significant after correction for multiple testing. These preliminary findings suggest possible connections between inflammation and the psychophysiological aspects of chronic LBP that warrant further investigation in larger cohorts.