The COPD assessment test correlates well with the computed tomography measurements in COPD patients in China

Figures & data

Table 1 Inclusion and exclusion criteria for COPD patients

Inclusion criteria

Exclusion criteria

1. Age 40–80 years 2. Male or female 3. COPD diagnosed according the GOLD guidelines 4. S table clinically, without change of medication or acute exacerbation within the past 6 weeks 5. No use of β2-receptor agonist or anticholinergic drugs at least 12 hours before attending the study 6. Forced expiratory volume in 1 second to forced vital capacity ratio <70% after use of bronchodilator 7. ≥10 pack-years history of smoking now or in the past 8. Capable of completing CAT and mMRC questionnaires 9. Informed consent obtained

Common exclusion criteria 1. Unstable cardiovascular disease, such as uncontrolled high blood pressure, congestive heart failure, angina, etc 2. Severe hepatic and renal dysfunction, malnutrition, malignant tumor, and severe anemia 3. Mental illness 4. History of taking regular corticosteroids or other immunosuppressive agents 5. Participation in other studies within the past 6 weeks Exclusion criteria related to lung 1. Arterial oxygen saturation <90% at rest 2. Acute exacerbation of COPD or pneumonia within the past 6 weeks 3. Diagnosis of other chronic lung disease (such as bronchiectasis, cystic fibrosis, asthma, interstitial lung disease, lung cancer, etc), a history of pulmonary bulla, or pneumonectomy or other lung surgery 4. Active pulmonary tuberculosis 5. History of chest radiation therapy, pulmonary rehabilitation therapy, or other therapies before attending this study

Abbreviations: CAT, COPD assessment test; COPD, chronic obstructive pulmonary disease; mMRC, modified Medical Research Council.

Table 2 Inclusion and exclusion criteria for normal control subjects

Inclusion criteria	Exclusion criteria
1. Age 40–80 years 2. Male or female 3. No illness, symptoms, or other discomfort 4. Capable of completing CAT and mMRC questionnaires 5. Informed consent obtained	1. History of pulmonary disease or other system diseases (acute or chronic) 2. Mental illness 3. History of taking corticosteroids or immunosuppressive agents 4. Have ever participated or participating in any health care activities

Table 3 Characteristics of all subjects

Characteristic	Control group n=49	GOLD I–II group n=30	GOLD III–IV group n=33	P
Age, years	65.1±10.3	68.6±10.1*	68.8±11.2*,+	0.20a
Sex, female/male	21/28	13/17	11/22	0.35b
BMI (kg/m^2)	23.6±2.9	23.2±3.2*	22.9±3.4*,+	0.52a
Smoking index	6.7±10.9	17.6±18.4***	22.8±28.2**,+	0.000a
mMRC grade	0.1±0.2	1.4±0.9**	2.6±0.7**,++	0.000a
FEV1%	100.3±13.7	63.1±7.2**	35.4±6.5**,++	0.000a
FEV1/FVC (%)	82.4±4.8	63.9±4.0**	45.3±7.4**,++	0.000a

Notes: Data are presented as means ± standard deviation. P-values were calculated by one-way analysis of variance, except where indicated otherwise.

* P>0.05

** P<0.01

*** P<0.05 versus control group

+ P>0.05

++ P<0.01 versus GOLD I–II group.

a One-way analysis of variance.

b Analysis of chi-square test.

Abbreviations: BMI, body mass index; mMRC, modified Medical Research Council.

Table 4 CAT score and CT measurements in the total subjects

	Control group	GOLD I–II group	GOLD III–IV group	P
CAT score	0.1±0.3	15.1±8.8**	24.9±7.0**,++	0.000
%WA (%)	75.3±3.6	77.9±5.6*	81.9±3.3**,++	0.000
WT/D (%)	25.8±2.5	27.1±2.9**	29.0±2.3**,+	0.000
%LAA (%)	2.2±1.3	7.0±2.8*	34.4±16.2**,++	0.000

Notes: Data are presented as means ± standard deviation. P-values were calculated by analysis of variance.

* P<0.05

** P<0.01 versus control group

+ P<0.05

++ P<0.01 versus GOLD I–II group.

Abbreviations: %LAA, percentage of low attenuation areas; %WA, wall area percentage; CAT, COPD assessment test; COPD, chronic obstructive pulmonary disease; CT, computed tomography; WT/D, ratio of airway wall thickness to total diameter.

Figure 1 Positive correlation between the CAT score and %LAA–950.

Notes: r=0.46, P=0.000.

Abbreviations: %LAA–950, percentage of pixels below −950 HU; CAT, chronic obstructive pulmonary disease assessment test.

Figure 2 Positive correlation between the CAT score and %WA.

Notes: r=0.48, P=0.000.

Abbreviations: %WA, wall area percentage; CAT, chronic obstructive pulmonary disease assessment test.

Figure 3 Positive correlation between the CAT score and WT/D.

Notes: r=0.37, P=0.003.
Abbreviations: CAT, chronic obstructive pulmonary disease assessment test; WT/D, ratio of airway wall thickness to total diameter.

Table 5 CT measurements in different CAT groups

CAT group	%WA (%)		WT/D (%)		%LAA (%)
	Mean ± SD	P	Mean ± SD	P	Mean ± SD	P
I (0–10)	75.8±6.4		26.6±2.7		5.8±2.8
		0.026		NS		0.009
II (11–20)	79.7±4.0		27.5±2.4		22.8±19.7
		NS		NS		NS
III (21–30)	81.2±4.2		28.7±2.7		23.1±18.1
		NS		NS		NS
IV (31–40)	83.0±3.4		29.5±2.7		24.3±15.6

Notes: Data are presented as means ± SD. P-values were calculated by one-way analysis of variance.

Abbreviations: %LAA, percentage of low attenuation areas; %WA, wall area percentage; CAT, COPD assessment test; COPD, chronic obstructive pulmonary disease; CT, computed tomography; NS, nonsignificant; SD, standard deviation; WT/D, ratio of airway wall thickness to total diameter.