TABLE 3.
Comparison of DXA-measured and anthropometrically derived body composition in ALS subjects from Cohort #1 (test cohort)1
| Equation | Mean ± SD | Difference from DXA | Ratio test equation/DXA | P value2 | Pearson's correlation (P value) |
|---|---|---|---|---|---|
| Body fat, % | |||||
| DXA | 29.0 ± 10.5 | ||||
| Jackson and Pollock | 22.9 ± 9.1 | 6.1 ± 5.2 | 0.79 | <0.001 | 0.87 (<0.001) |
| Durnin and Womersley | 27.2 ± 8.1 | 1.8 ± 4.7 | 0.94 | 0.09 | 0.90 (<0.001) |
| Deurenberg et al. (BMI) | 29.6 ± 7.0 | −0.9 ± 6.3 | 1.02 | 0.43 | 0.75 (<0.001) |
| FM, kg | |||||
| DXA | 19.6 ± 6.8 | ||||
| Jackson and Pollock | 15.6 ± 6.0 | 3.8 ± 3.9 | 0.80 | <0.001 | 0.86 (<0.001) |
| Durnin and Womersley | 18.7 ± 6.1 | 0.7 ± 3.0 | 0.95 | 0.29 | 0.92 (<0.001) |
| Deurenberg et al. (BMI) | 20.8 ± 5.6 | −1.2 ± 4.0 | 1.06 | 0.12 | 0.81 (<0.001) |
| FFM or LBM, kg | |||||
| DXA3 | 46.3 ± 10.0 | ||||
| Jackson and Pollock4 | 53.1 ± 10.2 | −8.3 ± 4.6 | 1.15 | <0.001 | 0.94 (<0.001) |
| Durnin and Womersley4 | 50.0 ± 10.2 | −5.2 ± 3.2 | 1.08 | <0.001 | 0.95 (<0.001) |
| Deurenberg et al. (BMI)4 | 49.8 ± 10.2 | −3.5 ± 4.5 | 1.07 | <0.001 | 0.90 (<0.001) |
1
n = 29. Values are means ± SDs, unless indicated otherwise. BMI in kg/m2. ALS, amyotrophic lateral sclerosis; FFM, fat-free mass; FM, fat mass; LBM, lean body mass.
2
P values are from paired t tests, compared to DXA.
3
FFM from DXA.
4
LBM from equations. The sum of FM and FFM from DXA is lower than the sum of FM and LBM from equations, because DXA calculates bone mass separately, whereas LBM includes bone mass.