Role of peripheral eosinophilia in acute exacerbation of chronic obstructive pulmonary disease

Table 1 Comparison of clinical characteristics, laboratory findings, pulmonary function test, and inhaled medications between EOS group and non-EOS group

Variables	EOS group (n = 176)	Non-EOS group (n = 449)	P value
Male (%)	166 (94.3)	384 (85.5)	0.004
BMI	23.52 ± 4.19	23.23 ± 4.23	0.441
Age, yr	74.90 ± 11.74	76.89 ± 10.09	0.049
Smoking, n (%)			0.054
Never	45 (25.6)	142 (31.6)
Current	54 (30.7)	98 (21.8)
Ex-smoker	77 (43.8)	209 (46.5)
Hemogram values
Leukocyte count, 109/ L	8723.92 ± 3447.99	11002.72 ± 4311.44	0.000
Neutrophil, %	64.50 ± 9.89	77.74 ± 9.86	0.000
Monocyte, %	6.96 ± 2.20	6.71 ± 3.05	0.253
Lymphocyte, %	21.30 ± 8.18	13.13 ± 8.50	0.000
Eosinophil count, %	6.47 ± 3.81	0.79 ± 0.84	0.000
Basophil, %	0.40 ± 0.30	0.19 ± 0.28	0.000
Hemoglobin, g/dL	13.25 ± 2.31	13.24 ± 2.11	0.942
Hematocrit, %	39.31 ± 6.33	39.37 ± 5.83	0.909
MCV, fL	88.58 ± 7.58	89.35 ± 6.99	0.228
Platelet count, 103/µL	228.14 ± 86.15	206.59 ± 70.09	0.001
Mean platelet volume, fL	9.63 ± 0.76	9.75 ± 0.81	0.106
Neutrophil count, 109/L	5715.46 ± 2872.96	8718.93 ± 3962.78	0.000
Lymphocyte count, 109/ L	1770.57 ± 822.48	1294.99 ± 840.47	0.000
Eosinophil count, 109/ L	543.18 ± 351.54	76.16 ± 82.77	0.000
Neutrophil-to-lymphocyte ratio	4.39 ± 6.29	10.59 ± 13.11	0.000
Infection status, n (%)
CXR infiltrate	18 (10.2)	83 (18.5)	0.016
Fever	9 (5.1)	51 (11.4)	0.026
Antibiotics	145 (82.4)	404 (90.0)	0.013
Inflammatory markers
CRP	2.08 ± 3.76	4.64 ± 5.75	0.000
Home noninvasive ventilation, n (%)	18 (10.2)	43 (9.6)	0.923
Comorbidities, n (%)
Neuromuscular disease	25 (14.2)	32 (7.1)	0.009
Ischemic heart disease	35 (19.9)	92 (20.5)	0.954
Cancer	8.0 (14)	30 (6.7)	0.705
ESRD	0 (0)	3 (0.6)	0.370
Hypertension	82 (46.6)	208 (46.3)	0.715
Diabetes mellitus	28 (15.9)	65 (14.5)	0.743
Liver cirrhosis	3 (1.7)	3 (0.6)	0.238
Autoimmune disease	1 (0.6)	9 (2.0)	0.327
Pulmonary function tests
FVC (L)	2.14 ± 0.77	1.94 ± 0.65	0.002
FVC % predicted	75.66 ± 27.52	73.16 ± 22.76	0.285
FEV1(L)	1.07 ± 0.43	1.02 ± 0.42	0.247
FEV1 % predicted	47.20 ± 17.70	48.55 ± 17.69	0.393
FEV1/FVC %	50.90 ± 12.70	53.12 ± 13.02	0.054
Bronchodilator response, n (%)	80 (45.5)	170 (37.9)	0.099
Inhaled medications before admission, n (%)
LAMA	13 (7.4)	32 (7.1)	0.910
LAMA + LABA	4 (2.3)	13 (2.9)	0.667
ICS + LABA	43 (24.4)	112 (24.9)	0.894
LAMA + LABA + ICS	68 (38.6)	155 (34.5)	0.334

Data are presented as mean ± SD and number (percentage). Independent samples t-test was used for comparison of continuous data. Chi-squared test was used for comparison of categorical variables. COPD: Chronic obstructive pulmonary disease; EOS group: Patients with eosinophil count ≥ 2%; Non-EOS group: Patients with eosinophil count < 2%; BMI: Body mass index; CRP: C-reactive protein; CXR: Chest X-ray; ESRD: End stage renal disease; MCV: Mean corpuscular volume; FEV1: Forced expiratory volume in one second; FVC: Forced vital capacity; ICS: Inhaled corticosteroids; LAMA: Long-acting muscarinic antagonists; LABA: Long-acting beta agonists.

Table 2 Comparison of length of hospital stay, steroid use, history of admissions and readmissions, and hospital discharge outcomes between the groups

Variables	EOS group (n = 176)	Non-EOS group (n = 449)	P value
Length of stay (d)	8.81 ± 5.95	10.00 ± 7.12	0.049
Prednisolone equivalent, mg	302.65 ± 341.35	373.35 ± 409.25	0.021
Major treatment (%)			0.095
None	4 (2.3)	6 (1.3)
Antibiotics only	25 (14.2)	36 (8)
Steroid only	27 (15.3)	75 (16.7)
Antibiotics + steroid	176 (68.2)	332 (73.9)
Hospitalization before admission within 12 mo, n (%)	111 (63.1)	242 (53.9)	0.047
No. of hospitalizations within 12 mo before admission	2.05 ± 2.41	1.44 ± 2.12	0.004
Hospitalizations after admission within 12 mo, n (%)	125 (71.0)	251 (55.9)	0.001
First readmission (days after discharge)	83.13 ± 90.01	73.85 ± 77.13	0.301
No. of readmissions within 12 mo	2.14 ± 2.34	1.53 ± 2.14	0.002
Discharge outcome, n (%)			0.204
Home discharge	176 (100.0)	441 (98.2)
RCW	0 (0)	4 (0.9)
Death	0 (0)	4 (0.9)

Data are present as mean ± SD and number (percentage). Independent samples t-test was used for comparison of continuous data. Chi-squared test was used for comparison of categorical variables. RCW: Respiratory care ward; EOS group: Patients with eosinophil count ≥ 2%; Non-EOS group: Patients with eosinophil count < 2%.

Table 3 Cox regression analysis of time to first chronic obstructive pulmonary disease-related readmission

Variables	Hazard ratio (adjusted)	95%CI: Lower–upper limit	P value
Group (EOS vs non-EOS)	1.488	1.195-1.854	< 0.001
FEV1 % predicted value	0.985	0.979-0.991	< 0.001
Age	1.010	1.000-1.020	0.049
BMI	0.985	0.961-1.009	0.208
Gender (male vs female)	0.951	0.692-1.305	0.754

Cox regression analysis was used to clarify the risk factors associated with time to first chronic obstructive pulmonary disease-related readmission. COPD: Chronic obstructive pulmonary disease; EOS: Patients with eosinophil count ≥ 2%; Non-EOS: Patients with eosinophil count < 2%; FEV1: Forced expiratory volume in one second; BMI: Body mass index; CI: Confidence interval.