Comparison of the COPD Assessment Test (CAT) and the Clinical COPD Questionnaire (CCQ) in a Clinical Population

Figures & data

Figure 1.  Data collection flow chart.

Table 1.  Patient characteristics by level of care

Measures	Primary care (n = 323)	Secondary care (n = 109)	p-value
Sex (432)
Female	193 (59.8%)	61 (56.0%)	Ref
Male	130 (40.2%)	48 (44.0%)	0.487
Age (432)
≤ 60	41 (12.7%)	14 (12.8%)	0.902
61–70	129 (39.9%)	46 (42.2%)	0.651
>70	153 (47.4%)	49 (45.0%)	Ref
Educational level*
Low	201 (64.0%)	66 (60.6%)	Ref
High	113 (36.0%)	43 (39.4%)	0.519
Smoking status**
Never	20 (6.2%)	10 (9.2%)	0.047
Occasional	228 (70.8%)	85 (78.0)	0.044
Ex	18 (5.6%)	4 (3.7%)	0.737
Current	56 (17.4%)	10 (9.2%)	Ref
Exacerbations***	107 (33.5%)	45 (42.1%)	0.112
Body Mass Index****
< 20	19 (6.0%)	9 (8.3%)	0.624
20–24	87 (27.4%)	33 (30.6%)	Ref
25–29	119 (37.5%)	41 (38.0%)	0.725
≥30	92 (29.0%)	25 (23.1%)	0.273
Hypertension	147 (45.5%)	46 (42.2%)	0.548
Heart disease**	77 (23.8%)	28 (25.9%)	0.662
Stroke	17 (5.3%)	3 (2.8%)	0.281
Diabetes	46 (14.2%)	17 (15.6%)	0.729
Depression**	77 (23.8%)	24 (22.2%)	0.731
COPD stage*****
1	56 (35.0%)	20 (23.3%)	Ref
2	71 (44.4%)	42 (48.8%)	0.121
3	30 (18.8%)	20 (23.3%)	0.108
4	3 (1.9%)	4 (4.7%)	0.103
CAT total score	16.49 (± 9.07)	18.51 (± 8.41)	0.041
CCQ total mean score	2.14 (± 1.36)	2.52 (± 1.40)	0.013

Data presented as n (%), or mean values (± standard deviations.) *N with available information = 423, **n = 431, ***n = 426, ****n = 425, *****n = 246. Ref = Reference.

Figure 2.  Correlation between CAT and CCQ scores. The regression equation describes the linear association between CAT total score and CCQ total mean score.

Table 2.  Factors influencing health status assessed by CAT and CCQ

Measures	CAT unadjusted	CAT adjusted	CCQ unadjusted	CCQ adjusted
Sex
Female	Ref	Ref	Ref	Ref
Male	-0.22 (-1.94 to 1.50)	1.02 (-0.62 to 2.66)	-0.11 (-0.37 to 0.16)	0.14 (-0.10 to 0.38)
Age
≤ 60	0.49 (-3.17 to 2.19)	0.34 (-2.22 to 2.90)	-0.24 (-0.66 to 0.17)	-0.14 (-0.52 to 0.24)
61–70	-0.56 (-2.37 to 1.26)	-0.26 (-1.96 to 1.45)	-0.08 (-0.36 to 0.20)	-0.02 (-0.27 to 0.23)
> 70	Ref	Ref	Ref	Ref
Educational level
Low	Ref	Ref	Ref	Ref
High	-2.17 (-3.19 to -0.41)	-1.54 (-3.21 to 0.12)	-0.43 (-0.70 to -0.16)	-0.32 (-0.57 to -0.08)
Exacerbations
0	Ref	Ref	Ref	Ref
≥ 1	6.99 (5.35 to 8.64)	6.84 (5.18 to 8.49)	1.33 (1.08 to 1.57)	1.29 (1.05 to 1.54)
Body Mass Index
< 20	5.88 (2.24 to 9.52)	4.97 (1.60 to 8.34)	1.00 (0.45 to 1.56)	0.77 (0.27 to 1.26)
≥ 20, < 25	Ref	Ref	Ref	Ref
≥ 25, < 30	-1.12 (-3.22 to 0.98)	-0.89 (-2.82 to 1.05)	-0.21 (-0.53 to 0.11)	-0.16 (-0.45 to 0.12)
≥ 30	-0.25 (-2.50 to 2.01)	0.06 (-2.02 to 2.15)	-0.10 (-0.44 to 0.25)	-0.06 (-0.36 to 0.25)
Heart disease	3.66 (1.72 to 5.61)	3.36 (1.49 to 5.23)	0.42 (0.12 to 0.72)	0.32 (0.05 to 0.59)
Anxiety/Depression	3.24 (1.26 to 5.22)	3.13 (1.30 to 4.97)	0.56 (0.26 to 0.86)	0.56 (0.29 to 0.83)

Results from separate univariate and multivariate linear regression with CAT and, respectively, CCQ. Data presented as unadjusted and adjusted regression coefficients (95% CI). Ref = Reference.

Table 3.  Comparison of factors influencing CAT and CCQ

Measures	CAT Standardised score	p-value	CCQ Standardised score	p-value
Sex	0.11 (-0.07 to 0.30)	0.224	0.10 (-0.07 to 0.28)	0.250
Age
≤ 60	0.04 (-0.25 to 0.32)	0.795	-0.10 (-0.37 to 0.17)	0.466
61–70	-0.03 (-0.22 to 0.16)	0.769	-0.02 (-0.20 to 0.17)	0.857
> 70	Ref		Ref
Educational level
Low	Ref		Ref
High	-0.17 (-0.36 to 0.014)	0.069	-0.23 (-0.41 to -0.06)	0.010
Exacerbations
0	Ref		Ref
≥ 1	0.77 (0.58 to 0.95)	<0.001	0.94 (0.76 to 1.12)	<0.001
Body Mass Index
< 20	0.56 (0.18 to 0.93)	0.004	0.56 (0.20 to 0.92)	0.003
≥ 20, < 25	Ref		Ref
≥ 25, < 30	-0.10 (-0.32 to 0.12)	0.368	-0.12 (-0.32 to 0.09)	0.266
≥ 30	0.01 (-0.23 to 0.24)	0.954	-0.04 (-0.26 to 0.18)	0.712
Heart disease	0.38 (0.17 to 0.59)	<0.001	0.23 (0.03 to 0.43)	0.023
Anxiety/Depression	0.35 (0.15 to 0.56)	0.001	0.41 (0.21 to 0.60)	<0.001

Results from multivariate linear regression with standardised CAT and CCQ scores. Data presented as adjusted regression coefficients (95% CI). Ref = Reference.

Figure 3.  Comparison CAT and CCQ. Adjusted regression coefficients (95%CI) for variables associated with health status in multiple linear regression with standardised CAT and CCQ scores.

Table 4.  Stratification and interaction analyses by sex

Measures	CAT Standardised score	CAT Standardised score	p-value	CCQ Standardised score	CCQ Standardised score	p-value
Female	Male	Female	Male	Age
Age
≤ 60	0.10 (-0.27 to 0.47)	-0.06 (-0.51 to 0.40)	0.455	-0.08 (-0.43 to 0.27)	-0.16 (-0.60 to 0.27)	0.502
61–70	-0.09 (-0.34 to 0.17)	0.08 (-0.21 to 0.38)	0.185	-0.11 (-0.35 to 0.13)	0.14 (-0.14 to 0.42)	0.086
> 70	Ref	Ref	Ref	Ref	Ref	Ref
Educational level
Low	Ref	Ref		Ref	Ref
High	-0.16 (-0.41 to 0.09)	-0.22 (-0.50 to 0.06)	0.888	-0.22 (-0.46 to 0.01)	-0.30 (-0.57 to -0.03)	0.997
Exacerbations
0	Ref	Ref		Ref
≥ 1	0.79 (0.55 to 1.02)	0.71 (0.41 to 1.02)	0.568	1.05 (0.83 to 1.27)	0.75 (0.45 to 1.04)	0.049
Body Mass Index
< 20	0.81 (0.35 to 1.27)	0.06 (-0.61 to 0.73)	0.239	0.89 (0.46 to 1.33)	-0.13 (-0.77 to 0.51)	0.017
≥ 0, < 25	Ref	Ref	Ref	Ref	Ref
≥ 5, < 30	0.13 (-0.16 to 0.42)	-0.42 (-0.75 to -0.08)	0.023	0.03 (-0.24 to 0.30)	-0.35 (-0.67 to -0.03)	0.155
≥ 30	0.06 (-0.25 to 0.37)	-0.11 (-0.48 to 0.25)	0.244	-0.01 (-0.30 to 0.28)	-0.13 (-0.48 to 0.22)	0.212
Heart disease	0.39 (0.08 to 0.70)	0.33 (0.04 to 0.62)	0.913	0.23 (-0.06 to 0.52)	0.22 (-0.05 to 0.50)	0.941
Anxiety/Depression	0.23 (-0.02 to 0.49)	0.54 (0.19 to 0.89)	0.123	0.31 (0.07 to 0.55)	0.57 (0.23 to 0.90)	0.145

Results from multivariate linear regression with standardised CAT and CCQ scores stratified by sex, and from interaction analysis with further adjustment for interaction terms for sex and each relevant variable. Data are presented as adjusted regression coefficients (95% CI) with p for interaction analyses. Ref = Reference.