Abstract
INTRODUCTION: Investigations of the relationship between waist circumference (WC) and bone mineral density (BMD) have inconsistent and incomprehensive results. We explored the association between WC and BMD at various sites in a large-scale population-based study. METHODS: We screened 5337 participants from National Health and Nutrition Examination Survey (NHANES) database. BMD was measured using dual-energy X-ray absorptiometry at various skeletal sites. The associations of WC with BMD were evaluated by weighted multivariable logistic regression models and conducted subgroup analyses for gender, age, and BMI. A weighted generalized additive model and a smooth curve fitting were performed to address non-linearity. RESULTS: Adjustments for all confounders, in males, WC was negatively correlated to BMD in different age and BMI groups (all the p < 0.05), except for in the lowest BMI group; in females, overall trends of relationships between WC and BMD were negative. However, statistical differences were insignificant in some cases. Additionally, every 1 cm increase in WC for individuals of all ages with normal BMI (18.5 ≤ BMI < 25) was associated with decrease in BMD at each skeletal site, as was the case for men with BMI ≥ 25 kg/m(2). For women, the negative association of WC with BMD was evident at the lumbar spine in the youngest age group (8 ≤ Age ≤ 18) with normal BMI. CONCLUSIONS: The nonlinear associations between WC and BMD at various skeletal sites are gender-, age- and BMI-specific in the NHANES (2006-2006).