Table 1.

Adjusted associations of exacerbation categories with lung density change

Exacerbation Category^*	Change in Adjusted Lung Density (g/L)
Exacerbation Category^*	Sample Size	Multivariable Model: Mean (95% CI)	P Value
Overall cohort
Former smokers			0.0005^†
0	1501	−3.27 (−3.81 to −2.74)	<0.0001
1–4	567	−4.16 (−4.91 to −3.41)	<0.0001
⩾5	284	−5.22 (−6.23 to −4.21)	<0.0001
Active smokers			0.494^†
0	1089	−4.89 (−5.63 to −4.16)	<0.0001
1–4	297	−5.58 (−6.84 to −4.32)	<0.0001
⩾5	136	−5.61 (−7.39 to −3.83)	<0.0001
Emphysema <5%
Former smokers			0.058^†
0	1013	−2.88 (−3.55 to −2.21)	<0.0001
1–4	287	−3.68 (−4.76 to −2.60)	<0.0001
⩾5	111	−4.74 (−6.39 to −3.09)	<0.0001
Active smokers			0.545^†
0	942	−4.40 (−5.18 to −3.62)	<0.0001
1–4	246	−4.84 (−6.22 to −3.47)	<0.0001
⩾5	106	−5.46 (−7.47 to −3.46)	0.0001
Emphysema ⩾5%
Former smokers			0.005^†
0	488	−3.73 (−4.60 to −2.87)	<0.0001
1–4	280	−4.68 (−5.67 to −3.69)	<0.0001
⩾5	173	−5.92 (−7.13 to −4.71)	<0.0001
Active smokers			0.492^†
0	147	−8.66 (−10.55 to −6.77)	<0.0001
1–4	51	−8.98 (−11.77 to −6.19)	<0.0001
⩾5	30	−6.62 (−10.12 to −3.12)	0.0002

Definition of abbreviation: CI = confidence interval.

All models adjusted for age, sex, race, height, body mass index, body mass index-squared, computed tomography noise, computed tomography noise-squared, study center, and computed tomography scanner type (random terms used for the last two).

Exacerbation categories on the basis of the total number over 5 years.

^{^†}

P value for interaction between exacerbation category and time (compares rates of change over time between exacerbation groups).