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

Table 2 Comparison between different densitometric parameters (whole lung CT scans) to assess progression of emphysema in patients treated with Prolastin versus placebo (mITT population)

PD15 (g/L)	Prolastin (n = 36)	Placebo (n = 35)
Change from baseline to last CT scan (mean ± SD)	-2.895 ± 4.739	-4.124 ± 4.147
Change from baseline to last CT scan (LS mean [SE])	-2.645 (0.526) < 0.0001^a	-4.117 (0.539) < 0.0001^a
Estimated treatment difference between LS mean changes from baseline (95% CI)	1.472 (0.009, 2.935)
p value for treatment difference^b	0.049
MLD (g/L)	Prolastin (n = 36)	Placebo (n = 35)
Change from baseline to last CT scan (mean ± SD)	-2.115 ± 7.937	-3.289 ± 5.949
Change from baseline to last CT scan (LS mean [SE])	-1.911 (0.788) 0.0181^a	-3.313 (0.801) 0.0001^a
Estimated treatment difference between LS mean changes from baseline (95% CI)	1.402 (-0.782, 3.586)
p value for treatment difference^b	0.204
VI-910 (%)	Prolastin (n = 36)	Placebo (n = 35)
Change from baseline to last CT scan (mean ± SD)	1.761 ± 4.511	2.209 ± 3.378
Change from baseline to last CT scan (LS mean [SE])	1.643 (0.508) 0.0019^a	2.254 (0.517) < 0.0001^a
Estimated treatment difference between LS mean changes from baseline (95% CI)	-0.611 (-2.019, 0.797)
p value for treatment difference^b	0.389
VI-950 (%)	Prolastin (n = 36)	Placebo (n = 35)
Change from baseline to last CT scan (mean ± SD)	1.994 ± 3.307	2.315 ± 2.578
Change from baseline to last CT scan (LS mean [SE])	1.924 (0.411) < 0.0001^a	2.356 (0.420) < 0.0001^a
Estimated treatment difference between LS mean changes from baseline (95% CI)	-0.432 (-1.573, 0.709)
p value for treatment difference^b	0.452

PD15, 15th percentile lung density; CT, computed tomography; SD, standard deviation; LS mean, least squares mean; SE, standard error; 95% CI, 95% confidence interval; MLD, mean lung density; VI-910, voxel index at a threshold of -910 (measured in %); VI-950, voxel index at a threshold of -950 (measured in %). ^ap values are for the comparison of change from baseline to last CT scan versus no change from baseline within the individual treatment groups. ^bProlastin treatment minus placebo (LS mean change).

ISSN: 1465-993X