|
Densitometric progression adjusted for lung volume using random coefficient model |
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| Variable |
Annual change, mean ± SE (95% CI) |
t |
p value for annual rate |
p value for volume |
|
|
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| Whole lung analysis |
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| WL Perc15 |
-2.13 ± 0.44 (-3.01, -1.24) |
-4.82 |
< 0.0001 |
< 0.0001 |
| WL VI-950 |
0.90 ± 0.19 (0.52, 1.29) |
4.72 |
< 0.0001 |
< 0.0001 |
| WL VI-910 |
1.16 ± 0.25 (0.66, 1.65) |
4.67 |
< 0.0001 |
< 0.0001 |
|
|
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| Single slice analysis |
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| UZPerc15 |
-2.02 ± 0.53 (-3.08, -0.97) |
-3.82 |
0.0003 |
< 0.0001 |
| UZ VI-950 |
0.60 ± 0.21 (0.18, 1.02) |
2.84 |
0.0057 |
< 0.0001 |
| UZ VI-910 |
0.94 ± 0.33 (0.29, 1.59) |
2.88 |
0.0051 |
< 0.0001 |
| LZ Perc15 |
-1.93 ± 0.58 (-3.07, -0.78) |
-3.34 |
0.0013 |
< 0.0001 |
| LZ VI-950 |
1.02 ± 0.32 (0.39, 1.65) |
3.22 |
0.0019 |
< 0.0001 |
| LZ VI-910 |
1.34 ± 0.38 (0.58, 2.1) |
3.52 |
0.0007 |
< 0.0001 |
|
|
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| Targeted sampling |
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| UT Perc15 |
-2.54 ± 0.62 (-3.77, -1.32) |
4.13 |
< .0001 |
< 0.0001 |
| UT VI-950 |
0.67 ± 0.22 (0.24, 1.10) |
3.11 |
0.0027 |
< 0.0001 |
| UT VI-910 |
1.28 ± 0.44 (0.42, 2.15) |
2.95 |
0.0042 |
< 0.0001 |
| MT Perc15 |
-2.94 ± 0.49 (-3.91, -1.97) |
-6.04 |
< 0.0001 |
< 0.0001 |
| MT VI-950 |
1.20 ± 0.24 (0.73, 1.67) |
5.08 |
< 0.0001 |
< 0.0001 |
| MT VI-910 |
1.78 ± 0.35 (1.08, 2.47) |
5.12 |
< 0.0001 |
< 0.0001 |
| LT Perc15 |
2.85 ± 0.61 (-4.07, -1.64) |
-4.68 |
< 0.0001 |
< 0.0001 |
| LT VI-950 |
1.28 ± 0.26 (0.76, 1.80) |
4.96 |
< 0.0001 |
< 0.0001 |
| LT VI-910 |
1.57 ± 0.29 (0.99, 2.15) |
5.37 |
< 0.0001 |
< 0.0001 |
|
WL, whole lung; UZ, upper zone single slice; LZ, lower zone single slice; ATl, apical third; MT, middle third; LT, lower third; SE, standard error; Perc15, 15th percentile point (measured in Hounsfield Units); VI-950, voxel index at a threshold of -950HU (measured in %); VI-910, voxel index at a threshold of -910HU (measured in %). The random coefficient model consists of outcome measurement as the dependent variable, time (year) as the fixed effect, volume as a time-dependent covariate, intercept and time (year) as random effects. The slope (coefficient for time variable) from the model is the estimated annual change adjusted for volume. | ||||
Parr et al. Respiratory Research 2008 9:21 doi:10.1186/1465-9921-9-21 |
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