Estimating Waist and Hip Circumference from Routine Clinical DXA

Introduction: Waist circumference and waist:hip ratio have body mass index-independent detrimental effects on health and mortality. Dual-energy X-ray absorptiometry (DXA) scans of the lumbar spine and hip can provide site-specific measures of soft-tissue thickness, and we hypothesized that this could be used to opportunistically estimate body circumference in patients undergoing DXA for osteoporosis assessment.

Methodology: We assessed the correlation and explained variance (as coefficient of determination, R²) between directly measured body circumference (waist circumference, hip circumference, and waist:hip circumference ratio) with DXA-derived measures of soft tissue thickness (spine DXA tissue thickness, hip DXA tissue thickness, and spine:hip tissue thickness ratio) in 214 women and 96 men (mean age 66.1 and 63.7 yr, respectively) undergoing DXA screening for osteoporosis.

Results: DXA-derived spine tissue thickness explained most of the variance in measured waist circumference (female R² 0.90, male R² 0.88). Explained variance was slightly lower for measured hip circumference (female R² 0.87, male R² 0.76) and waist:hip ratio (female R² 0.68, male R² 0.72). Final models predicted waist circumference with an adjusted R² 0.91, hip circumference with R² 0.86, and waist:hip ratio with R² 0.70.

Conclusion: Routine clinical DXA measurements of the spine and hip can be used to estimate body circumference measurements.