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Table 1 Characteristics of the Participants at Baseline

From: Lung function decline and incidence of chronic obstructive pulmonary disease in participants with spirometry-defined small airway dysfunction: a 15-year prospective cohort study in China

Characteristic

Pre-BD SAD

P value*

Post-BD SAD

P value*

Yes (N = 1419)

No (N = 3261)

Yes (N = 741)

No (N = 2174)

Age — years

59.0 ± 10.4

53.7 ± 10.6

 < 0.001

61.5 ± 9.8

53.8 ± 11.2

 < 0.001

Male — no. (%)

890 (62.7)

1304 (40.0)

 < 0.001

523 (70.6)

923 (42.5)

 < 0.001

Body mass index— kg/m2

22.5 ± 3.4

23.1 ± 3.3

 < 0.001

22.2 ± 3.5

23.3 ± 3.4

 < 0.001

Smoking status — no. (%)

  

 < 0.001

  

 < 0.001

 Never smoked

654 (46.1)

2256 (69.2)

 

286 (38.6)

1493 (68.7)

 

 Current smoking

494 (34.8)

694 (21.3)

 

280 (37.8)

441 (20.3)

 

 Former smoking

271 (19.1)

311 (9.5)

 

175 (23.6)

240 (11.0)

 

Smoking index — pack-year

21.7 ± 27.2

9.9 ± 19.9

 < 0.001

25.8 ± 28.8

11.2 ± 21.8

 < 0.001

Family history of respiratory diseases — no. (%)

189 (13.3)

404 (12.4)

0.379

92 (12.4)

274 (12.6)

0.894

Biomass exposure—no. (%)

757 (53.3)

1769 (54.2)

0.570

392 (52.9)

1165 (53.6)

0.746

Occupational history of dusts/gases/fumes—no. (%)

794 (56.0)

1855 (56.9)

0.555

427 (57.6)

1162 (53.4)

0.049

Pre-BD lung function

 FEV1 — L

1.86 ± 0.64

2.41 ± 0.60

 < 0.001

1.79 ± 0.65

2.46 ± 0.60

 < 0.001

 FEV1 of predicted value — %

72.3 ± 19.2

94.5 ± 13.1

 < 0.001

69.6 ± 20.8

94.8 ± 13.0

 < 0.001

 FVC — L

2.82 ± 0.84

2.96 ± 0.75

 < 0.001

2.80 ± 0.81

3.08 ± 0.77

 < 0.001

 FVC of predicted value — %

87.5 ± 19.3

93.6 ± 14.4

 < 0.001

86.7 ± 19.1

96.1 ± 14.5

 < 0.001

 FEV1/FVC — %

65.9 ± 1.3

81.9 ± 11.3

 < 0.001

63.4 ± 13.5

80.2 ± 6.6

 < 0.001

 MMEF — L/s

1.02 ± 0.48

2.43 ± 0.82

 < 0.001

0.97 ± 0.59

2.26 ± 0.90

 < 0.001

 MMEF of predicted value — %

42.1 ± 16.4

99.3 ± 27.6

 < 0.001

40.5 ± 22.1

90.0 ± 30.4

 < 0.001

 FEF50 — L/s

1.48 ± 0.73

3.23 ± 1.01

 < 0.001

1.42 ± 0.87

3.11 ± 1.07

 < 0.001

 FEF50 of predicted value — %

45.8 ± 19.4

100.2 ± 25.8

 < 0.001

44.3 ± 25.2

94.9 ± 27.8

 < 0.001

 FEF75 — L/s

0.39 ± 0.20

1.03 ± 0.46

 < 0.001

0.41 ± 0.29

0.93 ± 0.51

 < 0.001

 FEF75 of predicted value — %

43.4 ± 18.7

108.3 ± 42.7

 < 0.001

46.0 ± 28.8

94.7 ± 44.6

 < 0.001

Post-BD lung function

 FEV1 — L

-

-

-

1.85 ± 0.61

2.52 ± 0.60

 < 0.001

 FEV1 of predicted value — %

-

-

-

72.3 ± 19.6

97.4 ± 12.7

 < 0.001

 FVC — L

-

-

-

2.89 ± 0.88

3.07 ± 0.76

 < 0.001

 FVC of predicted value — %

-

-

-

89.5 ± 18.2

95.8 ± 13.9

 < 0.001

 FEV1/FVC — %

-

-

-

64.3 ± 13.2

82.7 ± 5.8

 < 0.001

 MMEF — L/s

-

-

-

0.98 ± 0.48

2.56 ± 0.89

 < 0.001

 MMEF of predicted value — %

-

-

-

40.4 ± 18.0

102.4 ± 28.7

 < 0.001

 FEF50 — L/s

-

-

-

1.46 ± 0.82

3.48 ± 1.04

 < 0.001

 FEF50 of predicted value — %

-

-

-

46.0 ± 24.2

106.5 ± 25.8

 < 0.001

 FEF75 — L/s

-

-

-

0.43 ± 0.29

1.08 ± 0.54

 < 0.001

 FEF75 of predicted value — %

-

-

-

49.5 ± 32.4

109.9 ± 45.9

 < 0.001

Airflow reversibility — no. (%)

-

-

-

113 (15.2)

126 (5.8)

 < 0.001

Chronic respiratory symptom — no. (%)

 Cough

241 (17.0)

510 (15.6)

0.249

134 (18.1)

363 (16.7)

0.386

 Sputum production

259 (18.3)

520 (15.9)

0.052

139 (18.8)

363 (16.7)

0.199

 Dyspnea

184 (13.0)

433 (13.3)

0.762

92 (12.4)

252 (11.6)

0.554

 Wheeze

97 (6.8)

222 (6.8)

0.972

58 (7.8)

144 (6.6)

0.265

  1. Data are mean ± standard deviation or n (%)
  2. BD = bronchodilator; SAD = small airway dysfunction; FEV1 = forced expiratory volume in one second; FVC = forced vital capacity; MMEF = maximal mid-expiratory flow; FEF50 = forced expiratory flow 50%; FEF75 = forced expiratory flow 75%
  3. * P values for continuous variables were calculated by Student’s t-test and P values for categorical variables were calculated by the chi-square test
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Respiratory Research

ISSN: 1465-993X

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