Table 1 Baseline characteristics (after adjusting smoking index)

Age, years

69(65.5,78)

70(67, 79)

0.035

Male, %

148(99.3%)

146(98.0%)

0.314

BMI, kg/m²

21.63(18.72,24.31)

21.16(18.67,24.45)

0.736

Smoking index, packets/year

40(30,56.5)

40(30, 60)

0.991

Spirometry(post-bronchodilation)

FEV1% predicted

29(21,39.6)

32.1(23,45)

0.116

FEV1/FVC, %

34(27.8,43.24)

38.89(31.1,46.85)

0.023

mMRC

3(2,4)

3(2,4)

0.159

CAT

23(18,28)

24.5(19,29)

0.429

Frequency of AEs in the last 12 months, times

2(1,2)

1(1,3)

0.011

Frequency of admission for AECOPD in the last 12 months, times

2(1,2)

1(1,2)

0.031

Laboratory investigations on admission

WBC count, x 10⁹/L

7.37(5.93,10.25)

7.23(5.97,9.73)

0.746

Neutrophil count, x 10⁹/L

5.44(4.02,7.66)

5.05(4.02,8.43)

0.478

Eosinophil count, x 10⁹/L

0.14(0.06,0.25)

0.13(0.05,0.23)

0.127

CRP, mg/l

6.45(2.97,29.63)

11.3(4.45,32.77)

0.050

PCT, mg/l

0.05(0.05, 0.12)

0.1(0.05, 0.14)

0.264

BNP, pg/ml

135(50, 930)

133(50, 560)

0.917

PaCO₂, mm/Hg

50(43,61.3)

50(42,62)

0.331

PaO₂, mm/Hg

68(56,80)

64(53,76)

0.489

SaO₂, %

93 (88,96)

92 (87,95)

0.704

ICS therapy during stable stage, %

81.2

77.9

0.474

Triple therapy during stable stage, %

38.3

27.5

0.049