C-reactive protein levels in stable COPD patients: a case-control study

Figures & data

Table 1 Characteristics of patients with COPD and control subjects

Parameters	COPD group (n=60)	Control group (n=30)	P-value
Mean age (years)	64.8±8.5	64.3±9.2	0.214
Male (%)	38 (63.3)	20 (66.7)	0.755
Smoking pack-years	46.5 (20.6–65.5)	30.0 (7.5–45.5)	0.193
Body mass index (kg/m^2)	25.3±4.5	28.1±4.3	0.006
Inhaled corticosteroid users	40 (66.7)	–	–
Oral corticosteroid users	1 (1.7)	–	–
C-reactive protein (mg/L)	3.2 (1.7–5.9)	2.1 (1.2–7.7)	0.620
Pulmonary function tests
FVC (% of predicted)	70.1±22.8	99.7±13.3	<0.0001
FEV1 (% of predicted)	43.5±19.2	102.4±18.3	<0.0001
FEV1/FVC	45.1±11.7	80.9±7.9	<0.0001
TLC (% of predicted)	122.1±23.3	NA	–
DLCO(% of predicted)	46.4±16.7	NA	–
Severity of COPD (GOLD criteria)
Stage I	2 (3.3)	–	–
Stage II	20 (33.3)	–	–
Stage III	21 (35.0)	–	–
Stage IV	17 (28.3)	–	–
BODE index	3.0 (1.5–5.0)	–	–
Exacerbations
O or 1 in the last year	42 (70.0)	–	–
≥2 in the last year	18 (30.0)	–	–

Note: Data are presented as mean ± SD, n (%), or median (interquartile range).

Abbreviations: NA, not available; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; TLC, total lung capacity; D_LCO, carbon monoxide diffusing capacity of the lung; GOLD, Global Initiative for Chronic Obstructive Lung Disease (stage I: FEV₁ ≥80% of predicted; II: 50%≤ FEV₁ <80% of predicted; III: 30%≤ FEV₁ <50% of predicted; IV: FEV₁ <30% of predicted); BODE, body mass index, measure of airflow obstruction, dyspnea score and exercise capacity; SD, standard deviation.

Table 2 Characteristics of patients and controls with normal and abnormal C-reactive protein levels

Parameters	COPD group (n=60)			Control group (n=30)
	Abnormal CRP (n=34)	Normal CRP (n=26)	P-value	Abnormal CRP (n=14)	Normal CRP (n=16)	P-value
Mean age (years)	64.7±9.0	64.8±7.9	0.988	64.9±8.7	63.9±9.9	0.776
Female (%)	17 (50.0)	5 (19.2)	0.014	10 (71.4)	10 (62.5)	0.709
Smoking pack-years	41 (19.0–62.5)	51 (32.1–72.0)	0.115	40 (35.0–79.5)	7.5 (3.0–24.4)	0.018
Body mass index (kg/m^2)	25.7±5.1	24.7±3.5	0.380	29.2±5.0	27.1±3.5	0.196
Inhaled corticosteroid users	25 (73.5)	15 (57.7)	0.271	–	–	–
Two or more exacerbations in the past year	10 (29.4)	8 (30.8)	0.999	–	–	–
FVC (% of predicted)	60.7±16.4	70.2±20.9	0.054	100.1±13.5	99.4±13.6	0.895
FEV1(% of predicted)	36.3±14.3	40.1±16.9	0.351	100.3±18.3	104.3±18.6	0.562
FEV1/FVC	44.8±12.1	46.2±11.1	0.646	78.5±7.1	83.1±8.2	0.117
BODE index	3.0 (1.0–5.3)	3.0 (2.0–5.0)	0.814	–	–	–
Severity of COPD (GOLD criteria)
Stage I	6 (17.6)	4 (15.4)	0.66	–	–	–
Stage II	2 (5.9)	4 (15.4)	–	–	–	–
Stage III	9 (26.5)	7 (26.9)	–	–	–	–
Stage IV	17 (50.0)	11 (42.3)	–	–	–	–

Notes: There was only one smoker in this subgroup. Data are presented as mean ± SD, n (%), or median (interquartile range).

Abbreviations: NA, not available; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; CRP, C-reactive protein; GOLD, Global Initiative for Chronic Obstructive Lung Disease (stage I: FEV₁ ≥80% of predicted; II: 50%≤ FEV₁ <80% of predicted; III: 30%≤ FEV₁ <50% of predicted; IV: FEV₁ <30% of predicted); BODE, body mass index, measure of airflow obstruction, dyspnea score and exercise capacity; SD, standard deviation.

Table 3 Bivariate correlations with C-reactive protein in COPD patients and controls

Parameters	COPD group		Control group
	r	P-value	r	P-value
Mean age (years)	−0.008	0.952	0.1	0.495
Body mass index (kg/m^2)	0.3	0.045*	0.3	0.097
Pulmonary function tests
FVC (% of predicted)	−0.3	0.023*	−0.08	0.682
FEV1(% of predicted)	−0.094	0.473	−0.2	0.323
FEV1/FVC	0.2	0.153	−0.2	0.343
TLC (% of predicted)	0.003	0.984	NA	–
DLCO (% of predicted)	0.043	0.764	NA	–
BODE index	0.050	0.713	NA	–

Note:

* P<0.05.

Abbreviations: NA, not available; COPD, chronic obstructive pulmonary disease; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; TLC, total lung capacity; D_LCO, carbon monoxide diffusing capacity of the lung; BODE, body mass index, measure of airflow obstruction, dyspnea score and exercise capacity.