Background: Low back disorder (LBD) is one of the greatest contributors to disability adjusted life years (DALYs) in the world. Inflammation results in proliferation of cytokines or consequent degradation products (collectively known as Inflammatory Biomarkers) that activate pain pathways which can result in non-specific LBD.
Purpose: Evaluate the relationship between inflammatory biomarkers, clinical presentation, disability and outcome of treatment in patients with LBD.
Methods: Three online databases were searched of randomized controlled trials (RCTs) and observational studies. The association between low back pain (LBP) and/or leg pain and/or back-specific disability scores and the expression of inflammatory biomarkers in patients with LBD were considered as primary outcomes. Standardized mean difference (SMD) and their 95% confidence intervals (CI) were evaluated. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to summarize the strength of evidence.
Results: Four RCTs and sixteen observational studies were included in the analysis of 1142 patients with LBD. There was a statistically significant reduction in back pain score (SMD=1.38 (95%CI=1.00 to 1.76)) and IL-1 beta (SMD=1.05 (95%CI=0.56 to 1.54)) and increase in the expression of CTX-1 (SMD=-0.54 (95%CI=-0.99 to -0.10)) and IL-10 (SMD=-0.91 (95%CI=-1.28 to -0.53)) levels post treatment. There was a significant relationship between increase in the expression of MCP-1 (r=4.46, (95%CI=2.72, 6.20), p=0.004) and reduction in the expression of hsCRP (r=-3.44, (95%CI=-5.16, -1.69), p=0.003) with increase in back pain. Significant relationship was also observed between increase in the expression of MCP-1 (r=4.34, (95%CI=1.30, 7.38), p=0.025) and reduction in the expression of IL-6 (r=-1.20, (95%CI=-1.20, -0.41), p=0.023) with increase in leg pain. Increase in the expression of IL-8 (r=3.36, (95%CI=2.71, 4.01), p<0.001) and reduction in the expression of hsCRP (r=-4.04, (95%CI=-4.54, -3.55), p<0.001) was also associated with increased disability score.
Conclusions: Inflammatory biomarkers play a significant role in the pathogenesis of LBD. CTX-1, IL-10 and IL-1 beta may be responsible for the decrease in back pain scores post treatment. There is a relationship between MCP-1, IL-6, IL-8 and hsCRP with clinical and functional assessments for LBD. Further studies will improve understanding of the pathogenesis of LBD and aid in targeted management strategies.