Objective: The purpose of this study was to explore the association between obesity (via body mass index [BMI]) and presence of low back pain (LBP) in a representative sample of US adults, aged ≥18 years.

Methods: This cross-sectional study used data from 32 060 respondents to the 2015 National Health Interview Survey. Body mass index (kg/m²) was calculated using reported height and weight and expressed as normal weight (<25 kg/m²), overweight (25 to <30 kg/m²), or obese (≥30 kg/m²); 3-month prevalence of reported LBP was the targeted outcome. Weighted univariate and multivariable logistic regression (adjusting for age, sex, race/ethnicity, education, and leisure-time physical activity) were performed. Interaction by sex and race/ethnicity was also explored.

Results: Findings suggest a statistically significant association between BMI categories and LBP. The adjusted odds ratios (95% confidence interval) of LBP in overweight and obese participants were higher than those in normal weight participants: 1.21 (1.11-1.32) and 1.55 (1.44-1.67), respectively. Both sex and race/ethnicity statistically significantly modified the association between BMI and LBP. Compared with normal weight white men (reference), odds ratios (95% confidence interval) of LBP were higher among obese white men, obese white women, and obese nonwhite women (1.28 [1.10, 1.48], 1.58 [1.36, 1.84], and 1.36 [1.16, 1.60], respectively), and lower in overweight, nonwhite men, and normal weight nonwhite men and women (0.80 [0.68, 0.94], 0.62 [0.51, 0.76], and 0.73 [0.61, 0.87], respectively).

Conclusion: Overweight and obesity were associated with increased odds of LBP. However, the measures of associations varied in magnitude and direction by race and sex groups.

Author keywords: Low Back Pain; Obesity; Overweight; Body Mass Index

Author affiliations: TP, GP: Department of Epidemiology, Human Genetics and Environmental Sciences, School of Public Health, University of Texas Health Science Center, Austin Regional Campus, Austin, Texas; AP: Department of Biostatistics, School of Public Health, University of Texas Health Science Center, Austin Regional Campus, Austin, Texas; GP: Department of Women's Health, The University of Texas at Austin, Dell Medical School, Austin, Texas

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