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Table 3 Sensitivity ratios for the different CT densitometric parameters (whole lung; analysis of covariance model)a

From: Exploring the optimum approach to the use of CT densitometry in a randomised placebo-controlled study of augmentation therapy in alpha 1-antitrypsin deficiency

 

Model with lung volume adjustment

Outcome measure

LS mean change from baseline

Standard error

Sensitivity indexb

F-testc

PD15 (g/L)

-4.12

0.539

7.64

-

MLD (g/L)

-3.31

0.801

4.14

< 0.05

VI-910 (%)

2.25

0.517

4.36

< 0.05

VI-950 (%)

2.36

0.420

5.61

NS

 

Model without lung volume adjustment

Outcome measure

LS mean change from baseline

Standard error

Sensitivity indexb

Reduction in sensitivity indexd

PD15 (g/L)

-4.24

0.771

5.50

2.14

MLD (g/L)

-3.49

1.221

2.86

1.28

VI-910 (%)

2.34

0.687

3.41

0.95

VI-950 (%)

2.41

0.514

4.69

0.92

  1. LS mean, least squares mean; PD15, 15th percentile lung density; MLD, mean lung density;
  2. VI-910, voxel index at a threshold of -910 (measured in %); VI-950, voxel index at a threshold of -950 (measured in %); NS, not significant. aResults based on estimates from endpoint analysis for placebo group only. bRatio of absolute value of mean change divided by standard error. cRatio of outcome measure as compared to PD15. dSensitivity index from model with lung volume adjustment minus sensitivity index from model without lung volume adjustment.