Decreased serum club cell secretory protein in asthma and chronic obstructive pulmonary disease overlap: a pilot study

Figures & data

Table 1 Comparison of the baseline characteristics of patients with different chronic inflammatory airway diseases

	Asthma n=32	COPD n=38	ACO n=37	P-value
Age	57.0 (47.0–66.8)a	67.0 (61.5–74.5)	64.0 (57.0–71.5)	0.001
Sex, male	12 (37.5%)	37 (97.4%)	33 (89.2%)	<0.001
BMI (kg/m^2)	23.2 (21.5–26.9)	22.3 (20.6–23.9)	24.6 (21.3–27.3)	0.039
Smoker	3 (9.4%)a	38 (100.0%)	37 (100.0%)c	<0.001
Ex-smoker	1 (3.1%)	17 (44.7%)	23 (62.2%)
Current smoker	2 (6.3%)	21 (55.3%)	14 (37.8%)
Smoking amount (pack-years)	0.0 (0.0–0.0)a	40.0 (33.8–54.8)	35.0 (20.0–44.5)c	<0.001
Comorbidities
Allergic rhinitis	19 (59.4%)a	2 (5.3%)b	17 (45.9%)	<0.001
Heart diseases	12 (37.5%)	16 (42.1%)	16 (43.2%)	0.585
Symptom scores
mMRC	0.0 (0.0–1.0)a	1.0 (0.0–2.0)	0.0 (0.0–1.0)	0.015
CAT	–	14.0 (10.0–22.0)	12.0 (9.5–16.8)	0.050
ACT	23.0 (21.0–24.0)	–	20.0 (14.0–22.3)c	0.001
SGRQ	10.5 (5.1–15.0)a	16.9 (11.0–32.6)	15.3 (8.1–23.6)	0.008
PFTs
FEV1 L	2.6 (2.0–2.8)a	1.7 (1.0–2.5)	1.9 (1.6–2.4)c	<0.001
FEV1 (%)	91.0 (78.3–102.8)a	66.5 (35.8–76.3)	65.0 (49.0–71.5)c	<0.001
FEV1/FVC (%)	76.0 (71.3–80.8)a	54.0 (34.8–58.3)	56.0 (44.5–64.5)c	<0.001
FEF25%–75% (%)	64.5 (47.0–92.8)a	21.5 (10.8–28.5)	27.0 (16.5–37.0)c	<0.001
BDR (mL)	105.0 (32.5–150.0)	50.0 (17.5–142.5)b	290.0 (200.0–400.0)c	<0.001
FRC (%)	107.0 (92.3–123.0)a	141.5 (128.8–157.0)	130.0 (110.0–149.5)c	<0.001
RV (%)	103.5 (86.3–125.8)a	142.0 (132.8–155.8)	138.0 (120.5–153.0)c	<0.001
DLCO (%)	97.0 (90.3–110.8)a	69.5 (47.5–98.8)	90.0 (67.5–98.5)c	<0.001
Frequent exacerbator (%)	1 (3.1%)	5 (13.2%)	6 (16.2%)	0.204

Notes: Data are presented as the median (IQR) for continuous variables and percentage (number) for categorical variables.

a Significantly different between asthma and COPD.

b Significantly different between COPD and ACO.

c Significantly different between asthma and ACO.

Abbreviations: ACO, asthma–COPD overlap; ACT, asthma control test; BDR, bronchodilator response; BMI, body mass index; CAT, COPD assessment test; DL_CO, diffusing capacity of the lung for carbon monoxide; FEF_25%–75%, forced expiratory flow at 25%–75% of FVC; FEV₁, forced expiratory volume in 1 second; FRC, functional residual capacity; FVC, forced vital capacity; mMRC, modified Medical Research Council; PFTs, pulmonary function tests; RV, residual volume; SGRQ, St George’s Respiratory Questionnaire.

Figure 1 Serum CC-16 levels in chronic inflammatory airway diseases according to disease classification.

Notes: (A) Serum CC-16 levels in patients with asthma, COPD, or ACO (asthma vs COPD, P=0.006; asthma vs ACO, P<0.001; COPD vs ACO, P=0.012); (B) Serum CC-16 levels in patients with asthma, COPD, smoking-related obstructive asthma, or COPD with a very positive BDR and/or eosinophilia (asthma vs COPD, P=0.006; asthma vs smoking-related obstructive asthma, P<0.001; asthma vs COPD with a very positive BDR and/or blood eosinophilia, P<0.001; COPD vs smoking related obstructive asthma, P=0.036; COPD vs COPD with a very positive BDR and/or blood eosinophilia, P=0.011; smoking-related obstructive asthma vs COPD with a very positive BDR and/or blood eosinophilia, P=0.248).
Abbreviations: ACO, asthma–COPD overlap; BDR, bronchodilator response; CC, club cell secretory protein; COPD, chronic obstructive pulmonary disease.

Figure 2 Correlation between serum CC-16 levels and parameters.

Notes: (A) Correlation between serum CC-16 levels and FEV₁ (R=0.423; P<0.001); (B) Correlation between serum CC-16 levels and FVC (R=0.192; P=0.047); (C) Correlation between serum CC-16 levels and FEV₁/FVC (R=0.397; P<0.001); (D) Correlation between serum CC-16 levels and DL_CO (R=0.255; P=0.008); (E) Correlation between serum CC-16 levels and smoking amount (R=−0.258; P=0.007); (F) Correlation between serum CC-16 levels and BDR (R=−0.313; P=0.001).
Abbreviations: BDR, bronchodilator response; CC, club cell secretory protein; DL_CO, diffusing capacity of the lung for carbon monoxide; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity.

Table 2 Comparison of frequent and nonfrequent exacerbators

	Frequent exacerbators n=12	Non-frequent exacerbators n=95	P-value
Age (years)	61.5 (54.3–72.3)	64.0 (57.0–70.0)	0.667
Sex, male	10 (83.3%)	72 (75.8%)	0.547
Smoker	10 (83.3%)	64 (67.3%)	0.010
Ex-smoker	9 (75.0%)	35 (36.8%)
Current smoker	1 (8.3%)	29 (30.5%)
Smoking amount (pack-years)	37.5 (12.5–48.8)	40.0 (33.8–54.8)	0.301
FEV1 (% predicted)	44.0 (28.3–75.8)	71.0 (55.0–85.0)	0.021
CC-16 (pg/mL)	4.09 (2.31–5.57)	5.49 (3.92–7.53)	0.023

Note: Data are presented as the median (IQR) for continuous variables and percentage (number) for categorical variables.

Abbreviations: CC, club cell secretory protein; FEV₁, forced expiratory volume in 1 second.