Work

Association between conicity index and osteoporosis/femoral bone mineral density in USA adults

Year: 2026

Type: article

Abstract: Aims Osteoporosis poses a substantial public health burden. The conicity index (C-index), which integrates waist circumference, weight, and height, is a validated measure of abdominal obesity. However, its association with osteoporosis and femoral bone mineral density (BMD) remains unclear. Methods This study analyzed data from 16,218 USA adults (aged ≥ 20 years) in the 2005 to 2020 National Health and Nutrition Examination Survey (NHANES). Associations between C-index and osteoporosis were assessed by weighted multivariable logistic regression, while associations between C-index and femoral BMD (total femur, neck, trochanter, intertrochanter) were evaluated by weighted multivariable linear regression. Potential non-linearity was explored via generalized additive models with smooth curve fitting. Threshold effect and dose-response analyses were performed, and robustness was tested by subgroup analyses. Results After full adjustment for confounders, participants in the highest C-index quartile (Q4) had significantly higher odds of osteoporosis than those in the lowest quartile (Q1) (OR 1.67 (95% CI 1.23 to 2.27); p = 0.001). Each one-unit increase in C-index was associated with statistically significant decreases in BMD, as follows: total femur (−0.17 g/cm 2 ), femoral neck (−0.18 g/cm 2 ), trochanter (−0.17 g/cm 2 ), and intertrochanter (−0.18 g/cm 2 ). These associations persisted in subgroup analyses. A non-linear relationship was identified between C-index and femoral BMD. Conclusion Elevated C-index independently predicts osteoporosis risk and femoral BMD reduction in USA adults, with critical thresholds indicating accelerated bone loss. It thus serves as a clinically actionable metric for osteoporosis risk stratification in abdominal obesity management. Cite this article: Bone Joint Res 2026;15(1):42–57.

Source: Bone and Joint Research

DOI: 10.1302/2046-3758.151.bjr-2025-0079.r2