Association Between Pain Intensity and Body Composition in Adults with Chronic Non-specific Low Back Pain: A Systematic Review and Meta-analysis

Introduction: This systematic review and meta-analysis evaluated the association between pain intensity and different body composition measures in adults suffering from chronic non-specific low back pain (CNLBP). Methods: A systematic literature search across five databases—PubMed, Embase, CINAHL, Web of Science, and the Cochrane Library—was conducted. It identified observational studies published until January 2024. A meta-analysis was conducted incorporating a random-effects approach with Fisher's Z transformation. A critical appraisal of the included studies' quality was conducted. Results: Twenty-two studies were included. Of those, 20 were meta-analyzed, revealing positive, very weak correlations between pain intensity and body mass index (r = 0.11; 95% CI: 0.04 to 0.18), waist–hip ratio (r = 0.10; 95% CI: −0.14 to 0.34) and waist circumference (r = 0.09; 95% CI: −0.28 to 0.44). Not pooled study findings (e.g., hip circumference and body fat percentage) were narratively summarized, revealing 13 positive and four negative associations between pain intensity and body composition measures. Studies showed a substantial risk of bias due to unadjusted confounding factors and limited transferability of findings. Conclusion: This systematic review and meta-analysis provided very low-quality evidence for a positive, very weak association between pain intensity and body composition measures in adults with overweight and obesity suffering from CNLBP. The included studies had a substantial risk of bias due to their observational and cross-sectional study designs, which prevents recommendations for clinical practice. Randomized controlled trials are needed to investigate the causal effect of interventions on body composition measures and pain intensity.