Peripheral Blood Eosinophil as a Biomarker in Outcomes of Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Figures & data

Table 1 Patients’ Characteristics on Admission of Quartile-Percentage of Eosinophil Cohorts

Variables		Percentage of Peripheral Blood Eosinophil^a
Groups		Overall	1	2	3	4
Participants, n		493	124	131	115	123
Gender, n (%)	Female	149(30.2)	38(30.6)	39(29.8)	37(32.2)	35(28.5)
	Male	344(69.8)	86(69.4)	92(70.2)	78(67.8)	88(71.5)
Year, median (IQR)		76(68–83)	76(69–83)	75(66–81)	77(67–83)	77(69–82)
BMI, median (IQR)		21.224(18.5–24.315)	21.1(17.8–24.22)	21.09(18.75–23.88)	20.98(18.83–24.86)	21.71(18.59–24.73)
Course of disease, year, median (IQR)		10(5–20)	10(5–29)	10(5–20)	10(5–15)	10(5–10)
Allergic history, n (%)		15(3)	3(2.4)	9(6.9)	1(0.9)	2(1.6)
Smoking history, n (%)	Current smoking	40(8.1)	15(12.1)	11(8.4)	8(7)	6(4.9)
	Ex-smoking	273(55.4)	67(54)	69(52.7)	68(59.1)	69(56.1)
	No-smoking	180(36.5)	42(33.9)	51(38.9)	39(33.9)	48(39)
	Smoking index, median	600(400–900)	600(300–800)	600(400–1000)	600(300–1000)	600(300–900)
HR, median (IQR)		88(78–96.5)	90(80–98.75)	89(80–96)	86(77–97)	82(76–93)
RR, median (IQR)		20(20–21)	20(20–22)	20(20–21)	20(20–21)	20(20–21)
LTOT, n (%)		246(49.9)	70(56.5)	71(54.2)	53(46.1)	52(42.3)
Daily treatment	ICS, n (%)	176(35.7)	48(38.7)	50(38.2)	36(31.3)	42(34.1)
	LABA, n (%)	176(35.7)	48(38.7)	50(38.2)	36(31.3)	42(34.1)
	LAMA, n (%)	106(21.5)	32(25.8)	24(18.3)	21(18.3)	29(23.6)
CAT, median (IQR)		18(14–26)	19.5(14.25–27)	18(14–26)	19(14–26)	18(13–26)
mMRC, median (IQR)		2(1–3)	2(1–3)	2(1–3)	2(1–3)	2(1–3)
Moderate or severe exacerbation history in previous year, median (IQR)		1(0–2)	1(0–2)	2(1–3)	2(0–3)	1(0–2)
Exacerbations leading to hospital or emergency admission in previous year, median (IQR)		1(0–2)	1(0–2)	1(0–3)	1(0–3)	1(0–2)
ABCD assessment, n (%)	A	124(25.2)	1(0.8)	39(31.5)	2(1.6)	82(66.1)
	B	131(26.6)	2(1.5)	29(22.1)	2(1.5)	98(74.8)
	C	115(23.3)	2(1.7)	34(29.6)	1(0.9)	78(67.8)
	D	123(24.9)	2(1.6)	36(29.3)	1(0.8)	84(68.3)
Pattern of admission, n (%)	Outpatient service	286(58)	69(55.6)	58(44.3)	78(67.8)	81(65.9)
	Emergency	207(42)	55(44.4)	73(55.7)	37(32.2)	42(34.1)

Notes: ^aPatients were grouped by quartile percentage (0, 0.7, 2.55) of blood eosinophils and divided into group 1, 2, 3 and 4 (from low to high).

Abbreviations: IQR, interquartile range: 25%–75%; n, number; BMI, body mass index; ICS, inhaled corticosteroids; LAMA, long-acting muscarinic antagonist; LABA, long-acting beta agonist; HR, heart rate; RR, respiratory rate; LTOT, long-term oxygen therapy; CAT, COPD assessment test; mMRC, modified British medical research council.

Table 2 Patients’ Characteristics on Admission of Quartile-Count of Eosinophil Cohorts

Variables		Absolute Count of Peripheral Blood Eosinophil^b
Groups		Overall	1	2	3	4
Participants, n		493	129	120	129	115
Gender, n (%)	Female	149(30.2)	41(31.8)	33(27.5)	44(34.1)	31(27)
	Male	344(69.8)	88(68.2)	87(72.5)	85(65.9)	84(73)
Year,median (IQR)		76(68–83)	76(69–83)	74.62(9.879)*	74.26(9.494)*	77(68–83)
BMI, median (IQR)		21.224(18.5–24.315)	20.96(17.78–22.22)	20.92(18.82–23.49)	21.41(18.79–24.92)	21.93(21.93–24.73)
Course of disease, year, median (IQR)		10(5–20)	10(5–20)	10(5.25–20)	10(3.5–10)	10(5–20)
Allergic history, n (%)		15(3)	3(2.3)	7(5.8)	3(2.3)	2(1.7)
Smoking history, n (%)	Current smoking	40(8.1)	17(13.2)	9(7.5)	9(7)	5(4.3)
	Ex-smoking	273(55.4)	70(54.3)	64(53.3)	71(55)	68(59.1)
	No-smoking	180(36.5)	42(32.6)	47(39.2)	49(38)	42(36.5)
	Smoking index, median	600(400–900)	600(300–800)	600(400–1000)	600(400–1000)	600(300–1000)
HR, median (IQR)		88(78–96.5)	89(80–98.5)	89(78–98)	84(76–95)	85(78–96)
RR, median (IQR)		20(20–21)	20(20–22)	20(20–21.75)	20(20–21)	20(20–21)
LTOT, n (%)		246(49.9)	75(58.1)	65(54.2)	55(42.6)	51(44.3)
Daily treatment	ICS, n (%)	176(35.7)	52(40.3)	42(35)	38(29.5)	44(38.3)
	LABA, n (%)	176(35.7)	52(40.3)	42(35)	38(29.5)	44(38.3)
	LAMA, n (%)	106(21.5)	34(26.4)	22(18.3)	21(16.3)	29(25.2)
CAT, median (IQR)		18(14–26)	20(15–27.5)	18(14–26)	17(13–25)	19(14–26)
mMRC, median (IQR)		2(1–3)	2(1–3)	2(1–3)	2(1–3)	2(1–3)
Moderate or severe exacerbation history in previous year, median (IQR)		1(0–2)	1(0–2)	1.5(0.25–3)	1(0–3)	1(0–3)
Exacerbations leading to hospital or emergency admission in previous year, median (IQR)		1(0–2)	1(0–2)	1(0.25–3)	1(0–2)	1(0–2)
ABCD assessment, n (%)	A	129(26.2)	1(0.8)	40(31)	2(1.6)	86(66.7)
	B	120(24.3)	1(0.8)	29(24.2)	2(1.7)	88(73.3)
	C	129(26.2)	3(2.3)	36(27.9)	2(1.6)	88(68.2)
	D	115(23.3)	2(1.7)	33(28.7)	0(0)	80(69.6)
Pattern of admission, n (%)	Outpatient service	286(58)	70(54.3)	55(45.8)	91(70.5)	70(60.9)
	Emergency	207(42)	59(45.7)	65(54.2)	38(29.5)	45(39.1)

Notes: ^bPatients were grouped by quartile absolute count (0, 0.05×109/L, 0.17×109/L) of blood eosinophils and divided into group 1, 2, 3 and 4 (from low to high). *Mean (SD, standard deviation).

Abbreviations: IQR, interquartile range: 25%–75%; n, number; BMI, body mass index; ICS, inhaled corticosteroids; LAMA, long-acting muscarinic antagonist; LABA, long-acting beta agonist; HR, heart rate; RR, respiratory rate; LTOT, long-term oxygen therapy; CAT, COPD assessment test; mMRC, modified British medical research council.

Table 3 Patients’ Laboratory Findings on Admission of Quartile-Percentage of Eosinophil Cohorts

Variables		Percentage of Peripheral Blood Eosinophil^c
Groups		Overall	1	2	3	4	P value
Arterial blood gas analysis	PH	7.416(7.3835–7.447)	7.411(7.370–7.449)	7.414(0.06)*	7.416(7.388–7.444)	7.417(0.041)*	0.783
	PaO2, mmHg	82(66.85–104)	87.05(66.85–103.75)	82.7(67–104)	83(64.9–108.7)	79.2(68–102)	0.972
	PaCO2,mmHg	41.2(36.5–50.55)	43.25(37.9–56.275)	41.2(34.8–53.7)	40.8(36.8–46)	40.9(36.4–47.1)	0.122
	SaO2%	96.2(93–98.1)	96(92.2–98)	96.3(93.3–98.3)	96(92–98)	96.6(94–98.1)	0.530
	FiO2	0.29(0.29–0.33)	0.29(0.29–0.33)	0.29(0.29–0.33)	0.29(0.29–0.30)	0.29(0.29–0.33)	0.104
	PaO2/FiO2	286.207(234.483–347.414)	286.078(237.972–338.054)	290(231.034–351.515)	295.238(243.81–359.31)	278.276(227.586–344.828)	0.710
	PaO2/SaO2	0.854(0.712–1.058)	0.904(0.722–1.07)	0.856(0.713–1.054)	0.856(0.7–1.102)	0.821(0.723–7.041)	0.963
Blood routine	Leukocyte count, 10^9/L	7.31(5.54–10.125)	8.33(6.268–11.898)	8.59(6.47–11.41)	7.22(5.54–9.05)	6.12(4.9–7.62)	0.000
	Neutrophil count, 10^9/L	5.43(3.75–8.305)	7.32(5.113–9.928)	6.79(4.64–9.51)	4.9(3.66–7.12)	3.91(2.97–5.16)	0.000
	Lymphocyte count, 10^9/L	1.06(0.7–1.51)	0.71(0.46–1.153)	1.03(0.7–1.49)	1.19(0.88–1.6)	1.18(0.89–1.76)	0.000
	Monocyte count, 10^9/L	0.5(0.36–0.69)	0.43(0.2425–0.598)	0.55(0.38–0.76)	0.54(0.43–0.67)	0.48(0.37–0.66)	0.000
	Eosinophil count, 10^9/L	0.05(0–0.17)	0(0)	0.02(0.01–0.03)	0.1(0.08–0.14)	0.26(0.2–0.4)	0.000
	Basophil count, 10^9/L	0.02(0.01–0.03)	0.01(0.01–0.02)	0.01(0.01–0.03)	0.02(0.01–0.04)	0.03(0.02–0.04)	0.000
	Neutrophil, %	76.1(66.4–83.9)	84.45(81.025–89.55)	79.3(74.1–85.1)	71.1(65.4–78.5)	64.1(57.6–71.4)	0.000
	Lymphocyte, %	14.7(9.3–21.05)	9.9(5.725–14.3)	13(8.5–18.3)	17.7(12–17.7)	20.3(15.2–27.1)	0.000
	Monocyte, %	6.9(5–8.8)	4.8(3.1–6.45)	6.5(4.9–8.5)	7.6(5.9–9.5)	0(6.5–8)	0.000
	Eosinophil, %	0.7(0–2.55)	0(0)	0.3(0.1–0.4)	1.4(1–2)	4.2(3.3–5.5)	0.000
	Basophil, %	0.2(0.1–0.4)	0.1(0.1–0.2)	0.2(0.1–0.3)	0.3(0.1–0.5)	0.5(0.2–0.7)	0.000

Notes: ^cPatients were grouped by quartile percentage (0, 0.7, 2.55) of blood eosinophils and divided into group 1, 2, 3 and 4 (from low to high). *Mean (SD, standard deviation).

Abbreviations: IQR, interquartile range: 25%–75%; E%, percent of blood eosinophil in white blood cell; E, absolute count of peripheral blood eosinophil.

Table 4 Patients’ Laboratory Findings on Admission of Quartile-Count of Eosinophil Cohorts

Variables		Overall	Absolute Count of Peripheral Blood Eosinophil^d
Groups			1	2	3	4	P value
Arterial blood gas analysis	PH	7.416(7.3835–7.447)	7.411(7.367–7.45)	7.421(7.387–7.456)	7.412(7.385–7.439)	7.417(0.045)*	0.421
	PaO2, mmHg	82(66.85–104)	85(64.95–102)	88.5(67.925–107.3)	80(64.9–105)	78(68–102)	0.365
	PaCO2, mmHg	41.2(36.5–50.55)	43.3(37.85–57)	40.3(34.75–51.175)	41.2(36.6–47.6)	40.6(36.5–46.5)	0.079
	SaO2%	96.2(93–98.1)	96(92–98)	97(94–98.65)	96(92–98)	96.6(94–98)	0.125
	FiO2	0.29(0.29–0.33)	0.29(0.29–0.33)	0.29(0.29–0.33)	0.29(0.29–0.315)	0.29(0.29–0.33)	0.286
	PaO2/FiO2	286.207(234.483–347.414)	279.31(234.483–336.207)	296.552(241.413–357.537)	280.952(234.483–359.785)	278.276(227.879–344.276)	0.338
	PaO2/SaO2	0.854(0.712–1.058)	0.88(0.707–1.046)	0.904(0.72–1.097)	0.833(0.699–1.071)	0.813(0.736–1.041)	0.455
Blood routine	Leukocyte count, 10^9/L	7.31(5.54–10.125)	7.79(5.85–10.95)	8.49(5.913–11.398)	6.64(5.09–9.015)	6.84(5.55–8.5)	0.001
	Neutrophil count, 10^9/L	5.43(3.75–8.305)	6.56(4.72–9.51)	6.71(4.2875–9.508)	4.63(3.475–6.92)	4.43(3.35–6.09)	0.000
	Lymphocyte count, 10^9/L	1.06(0.7–1.51)	0.69(0.46–1.115)	1.05(0.703–1.05)	1.21(0.87–1.665)	1.18(0.95–1.79)	0.000
	Monocyte count, 10^9/L	0.5(0.36–0.69)	0.41(0.24–0.585)	0.525(0.4–0.725)	0.52(0.385–0.685)	0.54(0.39–0.69)	0.000
	Eosinophil count, 10^9/L	0.05(0–0.17)	0(0)	0.02(0.01–0.04)	0.1(0.08–0.14)	0.27(0.21–0.41)	0.000
	Basophil count, 10^9/L	0.02(0.01–0.03)	0.01(0.01–0.02)	0.01(0.01–0.02)	0.02(0.01–0.04)	0.03(0.02–0.04)	0.000
	Neutrophil, %	76.1(66.4–83.9)	83.667(7.299)*	79.65(72.225–5.6)	70.3(63.5–77.25)	64.6(59.5–74.7)	0.000
	Lymphocyte, %	14.7(9.3–21.05)	10.4(6–14.6)	12.45(8.5–17.475)	18.3(12.3–26.95)	19.7(13.1–26.2)	0.000
	Monocyte, %	6.9(5–8.8)	5.1(3.1–6.55)	6.5(4.725–8.7)	7.7(5.95–9.3)	8.073(2.453)*	0.000
	Eosinophil, %	0.7(0–2.55)	0(0)	0.3(0.1–0.4)	1.5(1–2.35)	4.4(3.3–5.6)	0.000
	Basophil, %	0.2(0.1–0.4)	0.1(0.1–0.2)	0.2(0.1–0.2)	0.3(0.2–0.6)	0.4(0.2–0.6)	0.000

Notes: ^dPatients were grouped by quartile absolute count (0, 0.05×109/L, 0.17×109/L) of blood eosinophils and divided into group 1, 2, 3 and 4 (from low to high). *Mean (SD, standard deviation).

Abbreviations: IQR, interquartile range: 25%–75%; E%, percent of blood eosinophil in white blood cell; E, absolute count of peripheral blood eosinophil.

Figure 1 Flow chart of subjects.

Table 5 Comparison of Clinical Outcomes of Quartile-Percentage of Eosinophil Cohorts

Variables		Sum	Percentage of Peripheral Blood Eosinophil^e				P value
Groups			1	2	3	4
Participants, n		493	124	131	115	123	493
Stay of hospital, median (IQR)		11(9–14)	12(9.25–14)	11(8–14)	11(9–14)	10 (9–13) *	0.01
ICU admission, n (%)		6(1.2)	5(1)	0(0)	0(0)	1(0.2)	0.009*
Mortality, n (%)		5(1)	0(0)	4(0.8)	1(0.2)	0(0)	0.05*
Comorbidity, n (%)	Cardiovascular disease	371(75.3)	101(81.5)	99(75.6)	85(73.9)	86(69.9)	0.207
	Ischemic heart disease	73(14.8)	15(12.1)	21(16)	19(16.5)	18(14.6)	0.775
	Heart failure	188(38.1)	60(48.4)	56(42.7)	37(32.2)	35(28.5)	0.004
	Hypertension	207(42)	51(41.1)	56(42.7)	53(46.1)	47(38.2)	0.67
	Peripheral vascular disease	63(12.8)	18(14.5)	13(9.9)	15(13)	17(13.8)	0.714
	Arrhythmia	78(15.8)	25(20.2)	16(12.2)	19(16.5)	18(14.6)	0.365
	Diabetes	81(16.4)	19(15.3)	28(21.4)	19(16.5)	15(12.2)	0.258
	Bronchiectasis	87(17.6)	21(16.9)	27(20.6)	19(16.5)	20(17.3)	0.776
	Respiratory failure	215(43.6)	68(54.8)	64(48.9)	40(34.8)	43(35)	0.002
	Pulmonary heart disease	203(41.2)	63(50.8)	61(46.6)	37(32.2)	42(34.1)	0.005
Mechanical ventilation, n (%)	NIMV	147(29.8)	49(29.5)	43(32.8)	26(22.6)	29(23.6)	0.011
	IMV	4(0.8)	2(0.4)	1(0.2)	0(0)	1(0.2)	0.757*
	Duration of NIMV	238(139.75–309.75)	235 (124.5–305.5)	274.47 (139.482) **	282.5 (193.5–339)	214.29 (103.241)	0.381

Notes: ^ePatients were grouped by quartile percentage (0, 0.7, 2.55) of blood eosinophils and divided into group 1, 2, 3 and 4 (from low to high). *Fisher’s exact probability method; **Mean (SD, standard deviation).

Abbreviations: IQR, interquartile range: 25%–75%; N, number; E%, percent of blood eosinophil in white blood cell; E, absolute count of peripheral blood eosinophil; ICU, intensive care unit; NIMV, noninvasive mechanical ventilation; IMV, invasive mechanical ventilation.

Table 6 Comparison of Clinical Outcomes of Quartile-Count of Eosinophil Cohorts

Variables		Overall	Absolute Count of Peripheral Blood Eosinophil^f
Groups			1	2	3	4	P value
Participants, n		493	129	120	129	115
Stay of hospital, median (IQR)		11(9–14)	12(10–14)	10(8–14)	11(8–13)	10(9–13)	0.002
ICU admission, n (%)		6(1.2)	5(1)	0(0)	0(0)	1(0.2)	0.01
Mortality, n (%)		5(1)	1(0.2)	3(0.6)	1(0.2)	0(0)	0.283*
Comorbidity, n (%)	Cardiovascular disease	371(75.3)	103(79.8)	91(75.8)	97(75.2)	80(69.6)	0.325
	Ischemic heart disease	73(14.8)	15(11.6)	20(16.7)	19(14.7)	19(16.5)	0.663
	Heart failure	188(38.1)	62(48.1)	52(43.3)	39(30.2)	35(30.4)	0.005
	Hypertension	207(42)	50(38.8)	52(43.3)	57(44.2)	48(41.7)	0.824
	Peripheral vascular disease	63(12.8)	18(14)	11 (9.2)	18 (14)	16(13.9)	0.613
	Arrhythmia	78(15.8)	24(18.6)	18(15)	20(15.5)	16(13.9)	0.767
	Diabetes	81(16.4)	20(15.5)	25(20.8)	21(16.3)	15 (13)	0.433
	Bronchiectasis	87(17.6)	22(17.1)	24(20)	21(16.3)	20(17.4)	0.884
	Respiratory failure	215(43.6)	72(55.8)	52(43.3)	48(37.2)	43(37.4)	0.008
	Pulmonary heart disease	203(41.2)	67(51.9)	54(45)	44(34.1)	38(33)	0.005
Mechanical ventilation, n (%)	NIMV	147(29.8)	53(41.1)	37(30.8)	28(21.7)	29(25.2)	0.005
	IMV	4(0.8)	2(0.4)	1(0.2)	0(0)	1(0.2)	0.657*
	Duration of NIMV	238(139.75–309.75)	237(138.5–320)	242.49(148.295)**	242.71(116.665)**	241(164.25–304.25)	0.994

Notes: ^fPatients were grouped by quartile absolute count (0, 0.05×109/L, 0.17×109/L) of blood eosinophils and divided into group 1, 2, 3 and 4 (from low to high).IQR, interquartile range: 25%–75%; *Fisher’s exact probability method; **Mean (SD, standard deviation).

Abbreviations: N, number; E%, percent of blood eosinophil in white blood cell; E, absolute count of peripheral blood eosinophil; ICU, intensive care unit; NIMV, noninvasive mechanical ventilation; IMV, invasive mechanical ventilation.