Table 2—

Quantitative high-resolution computed tomography parameters by sex, age and smoking groups

	% Low-attenuation areas < -950 HU		AWT-Pi10 cm^#
	COPD cases	Controls	COPD cases	Controls
Subjects n	462	428	438	407
All subjects	7.02 (2.23–17.80)	0.52 (0.21–1.28)	0.494±0.033	0.477±0.029
Sex
Males	8.86	0.71	0.505	0.488
Females	4.74	0.32	0.474	0.463
p-value	0.0018	0.0001	<0.0001	<0.0001
Age yrs
<50	1.32	0.27	0.501	0.477
50–59	3.56	0.45	0.501	0.476
60–69	8.95	0.91	0.486	0.480
≥70	12.24	1.35	0.495	0.470
p-value	0.0001	0.0001	0.0025	0.4380
Smoking
Ex-smokers	9.72	0.65	0.493	0.477
Current smokers	4.86	0.35	0.495	0.476
p-value	0.0001	0.0001	0.4740	0.5683
Current smokers
<10 cigarettes·day⁻¹	6.02	0.31	0.480	0.473
10–19.9 cigarettes·day⁻¹	4.28	0.36	0.499	0.473
≥20 cigarettes·day⁻¹	5.33	0.26	0.501	0.487
p-value	0.1080	0.3414	0.0033	0.0493
Pack-years
<15	4.74	0.54	0.485	0.473
15–29.9	6.29	0.45	0.491	0.476
≥30	8.94	0.70	0.500	0.489
p-value	0.0733	0.3638	0.0033	0.0003

Data for all parameters are presented as median (25th–75th percentile) or mean±sd. Data for % low-attenuation areas < -950 HU are presented as median and for AWT-Pi10 (airway wall thickness for an airway with an internal perimeter of 10 mm) as mean. The p-values were calculated using Kruskall–Wallis (low-attenuation area) and ANOVA (AWT-Pi10). HU: Hounsfield units; COPD: chronic obstructive pulmonary disease. ^#: standardised measurement of airway wall thickness. The bold p-values indicate significance.