TABLE 4.
Comparison of FM and FFM computed using the ALS-specific equation and best-performing Deurenberg equations with DXA-measured values in Cohort #2 subjects (validation cohort)1
| Mean ± SD, kg | Difference from DXA, kg | Ratio test equation/DXA | P value2 | Pearson's correlation (P value) | |
|---|---|---|---|---|---|
| FM | |||||
| DXA | 29.7 ± 11.1 | ||||
| ALS-specific equation | 29.5 ± 14.0 | −0.2 ± 7.0 | 0.99 | 0.74 | 0.87 (<0.001) |
| Deurenberg equations | 28.7 ± 10.3 | −1.0 ± 5.7 | 0.97 | 0.07 | 0.86 (<0.001) |
| FFM or LBM | |||||
| DXA3 | 50.0 ± 11.7 | ||||
| ALS-specific equation4 | 52.5 ± 11.4 | 2.5 ± 5.9 | 1.05 | <0.001 | 0.87 (<0.001) |
| Deurenberg equations4 | 53.3 ± 12.1 | 3.3 ± 5.2 | 1.07 | <0.001 | 0.90 (<0.001) |
1
n = 104. Values are means ± SDs, unless indicated otherwise. ALS, amyotrophic lateral sclerosis; FFM, fat-free mass; FM, fat mass; LBM, lean body mass.
2
P values are from paired t tests, compared with 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.