COPD assessment test and severity of airflow limitation in patients with asthma, COPD, and asthma–COPD overlap syndrome

Figures & data

Table 1 Patient characteristics

	Asthma	COPD	ACOS	Chronic cough	P-value
	(N=138)	(N=99)	(N=51)	(N=44)	Asthma/ACOS	COPD/ACOS
Age, years	59.7±13.3	73.1±7.6	68.7±9.3	55.2±14.4	<0.001	NS
Male sex, %	47.1	92.9	84.3	36.4	<0.001	NS
Never smoker, %	61.6	0.0	0.0	50.0	<0.001	NS
Smoking, pack-years	11.5±21.2	68.6±35.1	59.3±28.9	11.9±16.6	<0.001	NS
CT-diagnosed emphysema, %	2.2	88.9	52.9	0.0	<0.001	<0.001
Blood eosinophil, %	6.8±10.9	3.3±5.6	6.1±7.6	4.7±6.3	NS	NS
IgE, IU/mL	515.2±605.7	143.2±137.2	596.7±674.1	146.9±147.7	NS	<0.05
FENO, ppb	28.1±24.7	17.7±12.1	35.6±29.9	11.5±13.1	NS	<0.001
Postbronchodilator
FVC, % predicted	92.1±16.1	86.2±19.1	81.6±16.9	94.7±16.3	<0.01	NS
FEV1, % predicted	100.5±18.7	69.6±25.5	70.6±21.3	110.3±16.9	<0.001	NS
FEV1/FVC, %	72.6±9.1	48.7±12.7	54.6±11.3	82.7±8.5	<0.001	NS
Response to beta2-agonist
FEV1, %	7.3±5.9	5.7±6.1	8.1±9.2	3.3±5.4	NS	NS
FEV1, mL	146.3±122.1	76.6±87.4	114.2±131.1	76.2±111.9	NS	NS
Previously treated, %
ICS use, %	97.8	41.4	94.1	NA	NS	<0.001
LABA use, %	76.1	55.6	92.2	NA	NS	<0.001
LAMA use, %	2.9	50.5	49.0	NA	<0.001	NS
CAT score	9.1±6.6	10.7±6.8	16.5±7.6	14.9±6.9	<0.001	<0.001
ACT score	21.7±4.0	NA	18.6±3.7	NA	NS	NA

Notes: Data are expressed as the mean ± standard deviation unless otherwise stated. Data shown as current at the time of the study. The airway reversibility in FEV₁ of >12% and 200 mL were confirmed previously at the time of diagnosis in all patients with asthma and ACOS.

Abbreviations: ACOS, asthma–COPD overlap syndrome; ACT, asthma control test; CAT, COPD assessment test; CT, computed tomography; FENO, fractional exhaled nitric oxide; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; ICS, inhaled corticosteroids; IgE, immunoglobulin E; LABA, long-acting beta2-agonist; LAMA, long-acting muscarinic antagonist; PAL, persistent airflow limitation; NA, not applicable; NS, not significant; ppb, parts per billion.

Figure 1 CAT component scores in patients with asthma, COPD, ACOS, and chronic cough.

Notes: Subgroups were compared by Dunn’s posttest after the Kruskal–Wallis test. Whiskers represent 95% confidence intervals. *P<0.05, **P<0.01, ***P<0.001.
Abbreviations: ACOS, asthma–COPD overlap syndrome; CAT, COPD assessment test; Ch cough, chronic cough; NS, not significant.

Table 2 Relationships between CAT scores and FEV₁

	CAT1	CAT2	CAT3	CAT4	CAT5	CAT6	CAT7	CAT8	%FEV1
									r	P-value
Asthma
CAT1		0.54	0.55	0.41	0.34	0.35	0.42	0.51	−0.09	0.281
CAT2	0.54		0.47	0.30	0.42	0.31	0.37	0.28	0.02	0.776
CAT3	0.55	0.47		0.52	0.58	0.59	0.55	0.57	−0.13	0.129
CAT4	0.41	0.30	0.52		0.42	0.31	0.30	0.46	−0.11	0.184
CAT5	0.34	0.42	0.58	0.42		0.69	0.51	0.52	0.04	0.663
CAT6	0.35	0.31	0.59	0.31	0.69		0.61	0.64	−0.09	0.299
CAT7	0.42	0.37	0.55	0.30	0.51	0.61		0.60	−0.05	0.589
CAT8	0.51	0.28	0.57	0.46	0.52	0.64	0.60		−0.10	0.264
COPD
CAT1		0.54	0.51	0.38	0.32	0.38	0.35	0.41	−0.18	0.083
CAT2	0.54		0.45	0.22	0.32	0.30	0.30	0.28	−0.16	0.115
CAT3	0.51	0.45		0.69	0.52	0.63	0.42	0.57	−0.44	<0.001
CAT4	0.38	0.22	0.69		0.49	0.57	0.36	0.46	−0.54	<0.001
CAT5	0.32	0.32	0.52	0.49		0.72	0.42	0.44	−0.24	0.016
CAT6	0.38	0.30	0.63	0.57	0.72		0.47	0.56	−0.32	0.001
CAT7	0.35	0.30	0.42	0.36	0.42	0.47		0.61	−0.24	0.019
CAT8	0.41	0.28	0.57	0.46	0.44	0.56	0.61		−0.33	0.001
ACOS
CAT1		0.64	0.51	0.41	0.37	0.26	0.29	0.30	−0.04	0.777
CAT2	0.64		0.44	0.33	0.36	0.38	0.17	0.28	0.17	0.238
CAT3	0.51	0.44		0.63	0.57	0.63	0.48	0.64	−0.15	0.297
CAT4	0.41	0.33	0.63		0.41	0.48	0.36	0.56	−0.34	0.013
CAT5	0.37	0.36	0.57	0.41		0.78	0.44	0.62	−0.13	0.378
CAT6	0.26	0.38	0.63	0.48	0.78		0.38	0.58	−0.15	0.288
CAT7	0.29	0.17	0.48	0.36	0.44	0.38		0.63	0.16	0.260
CAT8	0.30	0.28	0.64	0.56	0.62	0.58	0.63		−0.03	0.826

Note: Correlation coefficient among CAT scores and between CAT scores and %FEV₁ are shown.

Abbreviations: ACOS, asthma–COPD overlap syndrome; CAT, COPD assessment test; CAT1, cough; CAT2, phlegm; CAT3, chest tightness; CAT4, exertional dyspnea; CAT5, limited activity; CAT6, confidence in leaving home; CAT7, sleeplessness; CAT8, feeling of energy; %FEV₁, percent predicted forced expiratory volume in 1 second; r, coefficient.

Figure 2 Relationships between the CAT scores and %FEV₁ in patients with asthma, COPD, and ACOS.

Notes: The panels demonstrate the relationships between CAT total scores and %FEV₁ in patients with asthma (upper left panel), COPD (upper right panel), and ACOS (centre panel). Spearman’s rank test was used to assess the correlations.
Abbreviations: ACOS, asthma–COPD overlap syndrome; CAT, COPD assessment test; %FEV₁, percent predicted forced expiratory volume in 1 second.

Figure 3 Total CAT scores and exertional dyspnea scores adjusted by %FEV₁ in patients with asthma, COPD, ACOS, and chronic cough.

Notes: The adjusted CAT scores for total CAT scores and exertional dyspnea scores were calculated as follows: Adjusted CAT score = (CAT score) × %FEV₁/100. The adjusted score was introduced to evaluate the impacts of CAT scores in relation to the severity of airflow limitation. Whiskers represent 95% confidence intervals. NS denotes not significant, *P<0.05, ***P<0.001.
Abbreviations: ACOS, asthma–COPD overlap syndrome; CAT, COPD assessment test; Ch cough, chronic cough; %FEV₁, percent predicted forced expiratory volume in 1 second.

Figure 4 Relationships between the CAT scores and ACT scores in patients with asthma and ACOS.

Notes: The panels demonstrate relationships between CAT total scores and ACT scores in patients with asthma (left panel) and ACOS (right panel). Spearman’s rank test was used to assess the correlations. Dotted lines indicate low-impact levels based on the CAT (<10) scores and well-controlled levels on ACT (>19) scores.
Abbreviations: ACOS, asthma–COPD overlap syndrome; ACT, asthma control test; CAT, COPD assessment test.