The Association Between BMI and QCT-Derived Proximal Hip Structure and Strength in Older Men: A Cross-Sectional Study

To test our hypothesis of differential associations of body mass index with quantitative computed tomography parameters between non-obese and obese individuals, we evaluated the interactions between obesity and BMI, and stratified obese status to assess the relationships between BMI and QCT parameters expressed as SD change per unit increase of BMI in each stratum

Jian Shen


Scholarcy highlights

  • While obesity is a well-established risk factor for many chronic diseases, it is generally believed that individuals with higher body mass index have a low risk of osteoporosis, in part due to their increased bone mineral density 1,2
  • Obese men were 4 times more likely to have a load-to-strength ratio >1.0 compared to normal-weight men. In this cross-sectional analysis of BMI and quantitative computed tomography-derived structural and densitometric measures of proximal femur in older men, the relationship between BMI and hip QCT measures was significantly different between men categorized as non-obese and obese
  • Whereas for non-obese subjects, BMI was associated with a linear increase in femoral neck volumetric BMD, percent cortical volume, and minimal cross-sectional area, for obese men there was no further increase in these measures as BMI increased
  • In this study men meeting the criteria for obesity based on their BMI did have greater femoral neck volumetric BMD, bone size and cortical thickness compared to the overweight and normal weight men
  • Previous studies of older women found that relative to their body weight, heavier individuals have lower BMD and weaker radial and tibial geometry compared to those with normal weight 18. These findings provide evidence that increments in hip BMD and structural elements in the older obese men are not commensurate with their higher weight. Because these QCT-derived structural and densitometric parameters have been shown to significantly affect bone strength 10,28–31 and are associated with hip fracture risk independent of areal BMD 11, our findings may have some important implications for understanding the pathophysiology of hip fracture in subjects with high BMI
  • The FRAX algorithm uses a series of clinical risk factors, including BMI as a continuous variable, to calculate fracture risk 32
  • In non-obese men, increasing body mass index is associated with increasingly greater bone size, cortical thickness and cortical and trabecular bone mineral density. In individuals with BMI levels in the obese range, there is no further increase in those volumetric and structure parameters with additional increases in BMI

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