Effect of Community-Acquired Pneumonia on Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Figures & data

Figure 1. Study flow diagram. AECOPD, acute exacerbation of chronic obstructive pulmonary disease; CAP, community-acquired pneumonia.

Table 1. General characteristics of AECOPD patients with and without CAP.

	AECOPD with CAP (n = 200)	AECOPD without CAP (n = 178)	p value
Age, years (mean ± SD)	75.4 ± 9.1	74.9 ± 8.6	0.599
Sex, n (%)
Male	165 (82.5%)	153 (86.0%)	0.359
Female	35 (17.5%)	25 (14.0%)
Underlying diseases, n (%)
Hypertension	82 (41.0%)	80 (44.9%)	0.439
Diabetes	31 (15.5%)	30 (16.9%)	0.721
Cardiovascular disease	32 (16.0%)	32 (18.0%)	0.609
Cerebrovascular diseases	15 (7.5%)	16 (9.0%)	0.598
Chronic kidney disease	12 (6.0%)	13 (7.3%)	0.611
Malignancy	5 (2.5%)	7 (3.9%)	0.428
Tuberculosis	18 (9.0%)	19 (10.7%)	0.585
Charlson comorbidity Index, median (IQR)	1 (1–2)	1 (1–2)	0.336
Current smoker, n (%)	47 (24.5%)	59 (33.1%)	0.063
BMI, kg/m^2 (mean ± SD)	19.7 ± 3.5	20.3 ± 3.8	0.084
Long-term oxygen therapy, n (%)	39 (19.6%)	24 (14.0%)	0.158
Medications before an admission, n (%)
ICS^a	95 (47.5%)	66 (37.1%)	0.041
LABA^a	68 (34.0%)	57 (32.0%)	0.683
LAMA^a	16 (8.0%)	17 (9.6%)	0.594
Systemic corticosteroids^b	50 (25.0%)	33 (18.5%)	0.130
Antibiotics use^b	113 (56.5%)	83 (46.6%)	0.055
COPD categories^c, n
A/B/C/D	22/49/25/104	19/51/28/80	0.290
Lung functional parameters^d, median (IQR)
Postbronchodilator FEV1/FVC, %	50.1 (42.0–60.5)	50.0 (42.4–59.7)	0.929
Postbronchodilator FEV1, L	0.96 (0.81–1.33)	0.94 (0.76–1.23)	0.107
Postbronchodilator FEV1%, %	46.5 (37.0–57.0)	43.1 (32.8–58.0)	0.106

AECOPD, acute exacerbations of chronic obstructive pulmonary disease; CAP, community acquired pneumonia; BMI, body mass index; ICS, inhaled corticosteroid; LABA, long-acting β₂–agonist; LAMA, long-acting muscarinic antagonists; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity.

a Regularly prescribed for more than 3 months.

b Prescribed within 1 month.

c Grouped by global initiative for chronic obstructive lung disease.

d Data available for 350 patients, including 176 patients with AECOPD + CAP and 174 patients with AECOPD.

Table 2. Clinical characteristics, laboratory findings and outcomes of AECOPD patients with and without CAP.

	AECOPD with CAP (n = 200)	AECOPD without CAP (n = 178)	p value
Symptom, n (%)
Fever	70 (35.0%)	36 (20.2%)	0.001
Cough	193 (96.5%)	167 (93.8%)	0.222
Sputum	190 (95.0%)	163 (91.6%)	0.181
Pleuritic pain	26 (13.0%)	6 (3.4%)	0.001
Respite or Dyspnea	162 (81.0%)	156 (87.6%)	0.078
Laboratory findings, median (IQR)
White blood cell counts, × 10^9/L	8.9 (6.6–13.0)	8.1 (6.3–10.4)	0.005
Neutrophil counts, × 10^9/L	7.1 (4.6–10.8)	5.9 (4.1–8.0)	0.002
Lymphocyte counts, × 10^9/L	1.1 (0.8–1.6)	1.2 (0.9–1.8)	0.031
Eosinophil counts, × 10^9/L	0.08 (0.02–0.19)	0.11 (0.03–0.28)	0.043
Red blood cell counts, × 10^12/L	4.3 (3.9–4.8)	4.5 (4.1–4.9)	0.030
Hemoglobin, g/L	130 (118–143)	135 (122–145)	0.036
Albumin, g/L (mean ± SD)	35.1 ± 4.5	36.6 ± 4.3	<0.001
Urea nitrogen, mmol/L	5.7 (4.3–7.6)	5.3 (4.5–6.9)	0.213
Creatinine, μmol/L	78.0 (66.0–100.5)	76.0 (64.0–92.3)	0.613
PH	7.43 (7.40–7.46)	7.42 (7.39–7.44)	0.020
PaO2, mmHg	80.4 (68.0–95.0)	85.0 (73.6–100.2)	0.019
PaCO2, mmHg	40.7 (36.0–49.0)	42.4 (38.0–49.4)	0.204
PaO2/FiO2, mmHg	284.0 (236.5–342.0)	300.5 (266.8–357.0)	0.003
N terminal pro B type natriuretic peptide, ng/L	327.5 (106.0–1187.5)	151.5 (73.8–513.0)	<0.001
D-dimer, μg/L	0.67 (0.37–1.29)	0.49 (0.30–0.87)	0.002
C-reactive protein, mg/L	55.0 (25.4–94.7)	12.0 (6.0–30.6)	<0.001
Procalcitonin, ng/mL	0.08 (0.04–0.23)	0.04 (0.04–0.09)	<0.001
Outcomes
length of hospital stay, d, median (IQR)	9 (7–14)	8 (7–11)	0.015
Require NIMV, n (%)	22 (11.0%)	11 (6.1%)	0.097
Require IMV, n (%)	12 (5.0%)	2 (1.1%)	0.012

NIMV, noninvasive mechanical ventilation; IMV, invasive mechanical ventilation.

Figure 2. Predictors for the early discrimination between AECOPD with CAP and AECOPD without CAP. The filled rectangles and solid lines represent OR values and 95% CIs. Hosmer-Lemeshow goodness-of-fit test: χ2, 4.545; P, 0.715. ICS, inhaled corticosteroid; CRP, C-reactive protein; PCT, procalcitonin.

Figure 3. Kaplan–Meier analysis was used for cumulative survival, readmission and CAP readmission rates. (A) The cumulative survival rate was lower in the AECOPD with CAP group than in the AECOPD without CAP group (13.0% vs. 3.37%; HR: 4.099; 95% CI, 2.049–8.199; p < 0.001). (B) The readmission rate was similar between the AECOPD with CAP group and the AECOPD without CAP group (41.0% vs. 44.4%; HR: 1.051; 95% CI, 0.773–1.430; p = 0.530). (C) The patients with first-time exacerbation due to CAP were more likely to experience successive pneumonic exacerbation (58.5% vs. 31.3%; HR: 2.621; 95% CI, 1.647–4.170; p < 0.001).

Figure 4. Cox model was used to determine the risk factors influencing death and readmission. (A) The AECOPD with CAP group (HR: 3.117; 95% CI: 1.263–7.692; p = 0.014), FEV₁% < 30% (HR: 12.743; 95% CI: 3.759–43.196; p < 0.001) and NT-proBNP ≥ 300 ng/L (HR: 5.942; 95% CI: 2.251–15.686; p < 0.001) were associated with death. (B) The FEV₁% < 30% (HR: 1.766; 95% CI: 1.132–2.755; p = 0.012) and every 10 years higher for age (HR: 1.382; 95% CI: 1.144–1.669; p < 0.001) were risk factors for readmission. FEV₁, forced expiratory volume in 1 s; NT-proBNP, N terminal pro B-type natriuretic peptide.