Session Title: Osteoporosis and Metabolic Bone Disease
Session Type: Abstract Submissions (ACR)
Low Body Mass Index (BMI) is associated with low Bone Mineral Density (BMD) and subsequent risk of fragility fracture. Percentage body fat (%BF), which is measured by most DEXA scanners, has a correlation with BMD, however the relative contribution of %BF on osteoporosis has not been examined in detail. A higher %BF may be associated with a higher BMD when BMI is accounted for. Previous work from this unit has shown that the threshold for poor bone health is a BMI of 22.
Our aim was to determine the relationship between %BF and BMD in a population at risk of fracture.
Patients with a BMI of less than 22 were identified from a total population of 25896 who had been referred for Dual-Energy X-Ray Absorptiometry (DEXA) scanning between June 2004 and August 2010. The relationship between %BF (as measured by DEXA) and the mean BMD at both the femoral neck and lumbar spine were analysed using Stata 9.0 for Windows. Linear regression was used to determine the relationship between %BF and the BMD at both the lumbar spine and the femoral neck, adjusting for BMI.
2634 patients were included in the analysis which consisted of 2333 females; 88.6% of the population. Although there was a correlation between %BF and BMI (coeff, 0.06; 95% CI, 0.05, 0.07), the variance explained was low (adjusted-R squared value 0.07). When examining %BF and BMD and adjusting for BMI, there was a statistically significant negative association at the lumbar spine (coeff, -0.004; 95% CI, -0.006, -.0.004) and the femoral neck (coeff, -0.005; 95% CI, -0.007, -.0.004). This relationship was also observed in an only female cohort. A sensitivity analysis was performed using %BF alone, which still showed a negative correlation.
BMD was negatively influenced by %BF in this population with a low BMI, after adjusting for baseline BMI. A possible hypothesis is that body fat in this group has a paradoxical effect on bone health. Further work investigating this relationship in patients with a higher BMI will be performed.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-influence-of-percentage-body-fat-on-bone-mineral-density-in-thin-patients/