Association between a body shape index and bone mineral density in US adults based on NHANES data

The relationship between a body shape index (ABSI) and bone mineral density (BMD) remains uncertain, prompting further investigation. This study aims to elucidate the association between ABSI and BMD using data from the 2011-2018 National Health and Nutrition Examination Survey (NHANES), involving participants aged 20-60. ABSI was calculated using the formula: ABSI = 1000 × waist circumference (m)×weight (kg)^-2/3×height (m)^5/6. The analysis employed weighted multiple linear regression, smooth curve fitting, stratified analysis, and interaction tests to explore the relationship between ABSI and total BMD. The study included 10,291 participants, with a mean age of 39.11 ± 10.77 years, and 49.20% were women. The average ABSI was 80.21 ± 1.50. Total BMD, thoracic spine BMD, lumbar spine BMD, and pelvis BMD were measured, with mean values of 0.82 ± 0.11 g/cm², 1.03 ± 0.15 g/cm², and 1.24 ± 0.16 g/cm², respectively. A negative correlation between ABSI and total BMD was observed. In the fully adjusted model, individuals in the highest ABSI quartile had total BMD levels 0.045 g/cm² lower than those in the lowest quartile. Interaction tests showed a consistent association between ABSI and total BMD across subgroups, with variations in sex and BMI. This analysis of NHANES data confirms a persistent negative association between ABSI and BMD, suggesting that ABSI could be useful in osteoporosis prevention and diagnosis.