Association of a body shape index with femur bone mineral density among older adults: NHANES 2007-2018

This study investigated the relationship between A body shape index (ABSI) and bone mineral density (BMD) in older Americans and found a negative linear association, which was particularly pronounced in diabetic population. An early focus on ABSI in the elderly population will help in the prevention of osteoporosis. Objective A body shape index (ABSI) is an abdominal obesity index developed based on epidemiological statistics and high ABSI indicates that waist circumference (WC) is higher than expected for a given height and weight and corresponds to a more central concentration of body volume. The objective of this study was to determine whether there is a linear or nonlinear relationship between ABSI and total femur bone mineral density (BMD) in older Americans and whether the relationship between the ABSI and total femur BMD varies across populations. Methods This cross-sectional study was based on data from the 2007-2018 National Health and Nutrition Examination Survey (NHANES). Weighted multiple linear regression, restricted cubic spline (RCS) curves, subgroup analysis, and interaction tests were used to examine the association between ABSI and total femur BMD. Results This study included 2505 older adults. This study found a negative linear correlation between ABSI and total femur BMD (beta = -3.2, 95%CI: -5.0, -1.4, p < 0.001). When participants were grouped according to quartiles of ABSI, those in the upper quartile had lower total femur BMD compared to those in the bottom quartile of ABSI. This negative association remained consistent across gender, age, education level, smoking, physical activity and BMI subgroups. However, in the diabetes subgroup, ABSI showed a stronger negative association with total femur BMD. Conclusions The study shows a negative linear association between ABSI and total femur BMD in older Americans, with this negative association being stronger in the diabetic population.