Association between the Weight-Adjusted Waist Index and Low Back Pain: A Nationally Representative Cross-Sectional Study Using Data from the NHANES 1999–2004

Background: Evidence indicates that the correlation between obesity and low back pain (LBP) is likely multifactorial. To date, no studies have examined the correlation between the weight-adjusted waist index (WWI) and LBP. This study aimed to investigate the clinical and demographic profiles of individuals with and without LBP and examine the potential role of WWI as a risk factor and predictor of LBP. Methods: In this cross-sectional study, we examined a cohort of adult participants who provided comprehensive data on WWI and LBPfrom the 1999–2004 National Health and Nutrition Examination Survey. WWI was calculated by dividing waist circumference by the square root of body weight. We explored the association between WWI and LBPusing binary logistic regression modeling and propensity score matching. Results: The study included 8,041 participants aged over 20 years, of whom 3,134 had a history of LBP. A significant positive correlation was found between WWI and LBP in participants aged over 65 years, indicating that WWI is a strong predictor of LBP in old age groups. In contrast, the relationship between WWI and LBP was less consistent in participants aged 20–64 years, suggesting that other factors may have a more significant influence in other age groups. Conclusion: The findings of this study underscore the significance of the WWI as a potential predictor of LBP, particularly in older adults. The robust association observed between higher WWI and the increased prevalence of LBP in individuals highlights the importance of central adiposity as a clinical marker.