Chronic bronchitis is an independently associated factor for more symptom and high-risk groups

Figures & data

Table 1 Baseline characteristics of the COPD patients (n=1,106)

Characteristics	Non-CB, n=979 (88.5%)	CB, n=127 (11.5%)	P-value
Sex (male, n [%])	973 (91.6%)	127 (90.1%)	0.70
Age (years)	70.9±7.8	69.4±8.1	0.05
Current smoker (n [%])	256 (29.6%)	43 (39.45%)	0.04
BMI (kg/m^2)	22.8±3.4	22.3±3.3	0.13
mMRC	1.5±1.0	1.9±1.0	<0.01
SGRQ-C	33.0±18.6	46.1±22.0	<0.01
CAT	14.6±7.3	21.2±8.2	<0.01
Post-BD FVC (% predicted)	82.6±18.0	82.5±17.9	0.94
Post-BD FEV1 (% predicted)	57.1±17.1	51.4±13.7	<0.01
Post-BD FEV1/FVC (% predicted)	49.5±12.1	45.2±11.1	<0.01

Notes: Data are expressed as number (%) or mean ± standard deviation. Categorical variables were compared between groups using a χ² test. Continuous variables were assessed using a Student’s t-test. A P-value of less than 0.05 was considered to be statistically significant.

Abbreviations: CB, chronic bronchitis; BMI, body mass index; mMRC, modified Medical Research Council; SGRQ-C, St George Respiratory Questionnaire for COPD patients; CAT, COPD assessment test; BD, bronchodilator; FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 second.

Figure 1 Percentage of patients with CB according to GOLD stage.

Abbreviations: GOLD, Global initiative for chronic Obstructive Lung Disease; CB, chronic bronchitis.

Table 2 Comparison of each of the eight items of CAT scores between CB and non-CB patients

	Total CAT	CAT1	CAT2	CAT3	CAT4	CAT5	CAT6	CAT7	CAT8
CB (−)	14.62±7.30	1.67±1.24	1.96±1.29	1.51±1.36	3.22±1.33	1.32±1.40	1.29±1.39	1.32±1.40	2.34±1.24
CB (+)	21.16±8.16	3.22±1.32	3.27±1.26	2.20±1.53	3.77±1.24	2.02±1.48	2.04±1.57	1.91±1.51	2.74±1.30
Differences	6.54	1.55	1.31	0.69	0.55	0.70	0.75	0.59	0.40
P-value	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01

Notes: Data are expressed as mean ± standard deviation. Variables were assessed using a Student’s t-test. A P-value of less than 0.05 was considered to be statistically significant.

Abbreviations: CAT, COPD assessment test; CB, chronic bronchitis.

Figure 2 Comparison of CAT scores between CB and non-CB patients.

Notes: *P<0.05. Blue color indicates CB(−), orange color indicates CB(+).
Abbreviations: CAT, COPD assessment test; CB, chronic bronchitis.

Table 3 Multiple logistic regression analysis of the associated factors for the more symptom group

Variable	OR (95% CI)	P-value
CB phenotype	2.12 (1.19–3.77)	0.01
Sex (male)	0.93 (0.42–2.05)	0.86
Age	1.02 (1.00–1.04)	0.11
Current smoker	1.03 (0.74–1.44)	0.87
Post-BD FEV1 (% predicted)	0.97 (0.97–0.98)	<0.01

Notes: Hosmer–Lemeshow goodness of fit; P=0.89.

Abbreviations: OR, odds ratio; CI, confidence interval; CB, chronic bronchitis; BD, bronchodilator; FEV₁, forced expiratory volume in 1 second.

Table 4 Multiple logistic regression analysis of associated factors for the high-risk group

Variable	OR (95% CI)	P-value
CB phenotype	1.55 (1.03–2.34)	0.04
Sex (male)	1.40 (0.72–2.72)	0.33
Age	1.00 (0.98–1.02)	0.97
Current smoker	0.80 (0.60–1.05)	0.04

Notes: Hosmer–Lemeshow goodness of fit; P=0.30.

Abbreviations: OR, odds ratio; CI, confidence interval; CB, chronic bronchitis.