Traditional, central obesity, and metabolic indices: which metrics better reflect osteoarthritis risk? A cross-sectional study in U.S. adults

Background: Obesity is a major risk factor for osteoarthritis (OA), yet traditional metrics like body mass index (BMI) inadequately capture heterogeneity relevant to OA pathogenesis. This study systematically compared the associational performance of 10 anthropometric indices across three categories – general (BMI, waist circumference), abdominal (waist weight index [WWI], conicity index [C-index], body roundness index, waist-to-height ratio, a body shape index), and metabolic (visceral adiposity index [VAI], lipid accumulation product [LAP], cardiometabolic index [CMI]) – to identify research-significant OA association indicators. Methods: A cross-sectional analysis of 7734 U.S. adults (NHANES 2011–2018) evaluated associations between obesity indices and self-reported OA. The strength and shape of associations were assessed using multivariable-adjusted logistic regression, area under the ROC curve (ROC-AUC) comparisons, and restricted cubic spline analyses. Results: Among all cases, abdominal indices WWI (AUC: male 0.675, female: 0.661) and C-index (AUC: male: 0.691, female: 0.662) showed statistically higher discriminative capacity than BMI (AUC: male 0.604, female 0.602) and metabolic indices (VAI/CMI AUC <0.6). Adjusted models identified significantly elevated OA odds for the highest vs. lowest tertiles of WWI (odds ratio [OR] = 1.43) and C-index (OR = 1.45). Nonlinear relationships and ROC analysis were observed via spline analyses, with steeper risk gradients beyond WWI (cutoffs: male: 11.16, female: 11.11) and C-index (cutoffs: male: 1.34, female: 1.31). WWI/C-index maintained stronger OA associations in overweight/obese individuals (BMI ≥ 25). LAP showed isolated associations only in normal-weight subgroups (BMI < 25). Conclusion: Central adiposity indices (WWI, C-index) demonstrated stronger associations with OA prevalence than traditional and metabolic metrics, potentially through their dual sensitivity to biomechanical stress and adipokine dysregulation. While combining BMI with WWI or C-index may improve research-based risk profiling, future studies should establish population-specific reference ranges before considering clinical application.