2011 Young Investigator Award winner: Increased fat mass is associated with high levels of low back pain intensity and disability

STUDY DESIGN: A cross-sectional study. OBJECTIVE: To determine whether body composition is associated with low back pain intensity and/or disability. SUMMARY OF BACKGROUND DATA: The relationship between obesity and low back pain and disability is unclear. No study has examined the role of body composition in low back pain and disability. METHODS: A total of 135 participants (25-62 years), with a range of body mass indices (18-55 kg/m), were recruited for a study examining the relationship between obesity and musculoskeletal disease. Participants completed the Chronic Back Pain Grade Questionnaire, which examines individuals' levels of low back pain intensity and disability. Body composition was assessed using dual radiograph absorptiometry. RESULTS: Body mass index was associated with higher levels of back pain intensity (Odds ratio [OR] = 1.35; 95% confidence interval [CI] = 1.09, 1.67) and disability (OR = 1.66; 95% CI = 1.31, 2.09). Higher levels of pain intensity were positively associated with total body (OR = 1.19; 95% CI = 1.04, 1.38) and lower limb fat mass (OR = 1.51; 95% CI = 1.04, 2.20), independent of lean tissue mass. There were also positive associations between higher levels of low back disability and total body (OR = 1.41; 95% CI = 1.20, 1.67) and upper (OR = 1.67; 95% CI = 1.27, 2.19) and lower (OR = 2.29; 95% CI = 1.51, 3.49) limbs fat mass. Similar relationships were observed with trunk, android, and gynoid fat mass. After adjusting for confounders, no measures of lean tissue mass were associated with higher pain intensity or disability (P > 0.10). CONCLUSION: Greater fat, but not lean tissue mass, was associated with high levels of low back pain intensity and disability. Longitudinal investigation is needed to determine whether fat mass is predictive of low back pain and disability, as this may have important implications for further prevention strategies. Understanding the mechanism for these relationships may provide novel approaches to managing low back pain.