U-shaped relationship between body roundness index and osteoarthritis risk among middle-aged and older Chinese adults: a cross-sectional analysis.

BACKGROUND

Osteoarthritis (OA) has been linked to obesity, although the specific contribution of visceral fat remains a topic of ongoing investigation. The body roundness index (BRI) has been proposed as a more precise measure of overall and visceral adiposity compared with traditional indices. The potential association between BRI and the risk of OA has not been fully elucidated.

METHODS

Data were obtained from 8803 participants in the China Health and Retirement Longitudinal Study (CHARLS). Logistic regression analysis was applied to evaluate the association between BRI and OA risk. Stratified analyses were conducted across different subgroups, and smoothed curve fitting techniques were used to visualize the results.

RESULTS

Weighted logistic regression analysis and smoothed curve fitting demonstrated a U-shaped association between BRI and OA risk, with higher OA risk observed at both low and high extremes of BRI, relative to an inflection point. Stratified analyses indicated that this relationship varied by gender and ethnicity. Women exhibited a stronger association between higher BRI and OA risk compared with men [odds ratio (OR) 1.01 (0.86-1.06) vs. 1.07 (1.03-1.11)]. Lower BRI values appeared to be more protective among women. Minority populations demonstrated higher optimal BRI values compared with Han Chinese populations. No significant modifying effects were identified for other factors beyond gender and ethnicity.

CONCLUSION

A significant U-shaped relationship was observed between BRI and OA risk, with both low and high BRI values associated with increased risk. The association was particularly evident among women and ethnic minority populations. These findings highlight the importance of monitoring visceral adiposity as a modifiable factor in OA risk management. Key Points • A nonlinear U-shaped association exists between body roundness index (BRI) and osteoarthritis risk, with increased risk at both low and high BRI extremes. • The BRI-osteoarthritis relationship is modified by gender and ethnicity, demonstrating a stronger association in women and ethnic minority populations. • BRI may serve as a superior anthropometric indicator for visceral adiposity, offering a practical tool for identifying individuals at elevated risk for osteoarthritis.