Association between the body roundness index and chronic pain among adults in the United States: a cross-sectional study.

Background: Chronic pain is a significant public health concern in the United States. Obesity is associated with chronic pain. The body mass index may not accurately assess the health risks of obesity, and the body roundness index (BRI), a novel anthropometric indicator, may be more appropriate. However, the association between the BRI and chronic pain has not been validated. Therefore, this study examined the association between the BRI and chronic pain among adults in the United States.

Methods: This cross-sectional study analyzed data from adult participants in the 1999-2004 National Health and Nutrition Examination Survey. Chronic pain was defined as self-reported pain lasting 3 months or more in the past year. The BRI was calculated using height and waist circumference. Multivariable logistic regression models and restricted cubic splines were used to assess the association between the BRI and chronic pain. Subgroup analyses were performed to explore confounder effects.

Results: Of the 11,599 participants aged 20 years or older, 1690 (15.92%) had chronic pain. In fully adjusted models, the BRI was positively associated with chronic pain [odds ratio (OR) = 1.05, 95% confidence interval (CI) = 1.02-1.09]. Compared with participants in the lowest BRI quintile (Q1), those in the highest quintile (Q5) had an adjusted OR of 1.28 (95% CI = 1.07-1.54) for chronic pain. The multivariable restricted cubic spline showed a nonlinear association between the BRI and chronic pain. In two piecewise regression models, participants with BRI ≥ 4.63 had an adjusted OR of 1.07 (95% CI = 1.00-1.13) for chronic pain; however, no correlation was observed for participants with the BRI < 4.63. Further subgroup analyses revealed no significant interactions between these variables.

Conclusion: Higher BRI was associated with an increased risk of chronic pain, indicating that the BRI was a significant risk factor. Therefore, regular monitoring and preventive measures are required to maintain optimal BRI levels and prevent chronic pain.