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Table 1 Demographic characteristics, clinical variables, and particulate matter exposure of non-DET (n = 76) and DET (n = 78)

From: Chronic exposure to diesel exhaust may cause small airway wall thickening without lumen narrowing: a quantitative computerized tomography study in Chinese diesel engine testers

Variable Non-DET DET P values
N 76 78  
Demographics
 Age (yr, M ± SD) 36.4 ± 10.9 36.2 ± 8.0 0.89a
 Male sex (n, %) 76, 100 78, 100  
 Height (cm, M ± SD) 172.3 ± 5.9 173.0 ± 5.3 0.41a
 BMI (kg/m2, M ± SD) 25.7 ± 4.4 25.7 ± 3.4 0.99a
 Smoking Status    0.004b
  Never smoker (n, %) 33, 43.4 15, 19.2  
  Current smoker (n, %) 34, 44.7 54, 69.2  
  Former smoker (n, %) 9, 11.8 9, 11.5  
 Packyears in ever smokers (Mdn, Q1 - Q3) 13.5, 6.0–24.0 6.5, 2.6–15.0 0.008c
Particulate matter exposure
 DE exposure history (yr, M ± SD) 11.7 ± 6.3  
 PM2.5 (μg/m3, n, GSM, GSD) 5, 130.0, 1.2 4, 430.8, 2.3  
 CCAM (%, n, Mdn, Q1 - Q3) 53, 1.67, 1.20–2.19 53, 4.29, 3.07–6.49 < 0.001c
Self-reported symptom in past one year
 Coughing for ≥3 mo (n, %) 0, 0.0 2, 2.6 0.50b
 Phlegm for ≥3 mo (n, %) 1, 1.3 6, 7.7 0.12b
Radiographic diagnosis
 Emphysema (n, %) 4, 5.3 1, 1.3 0.21b
 Pulmonary fibrosis (n, %) 0, 0.0 0, 0.0 NC
 GGO (n, %) 0, 0.0 0, 0.0 NC
 Total lung volume (ml, M ± SD) 5054.1 ± 954.4 5020.4 ± 969.0 0.83a
Spirometry
 FEV1 (L/s, M ± SD) 3.64 ± 0.62 3.53 ± 0.42 0.020d
 FEV1% predicted (%, M ± SD) 98.02 ± 10.75 94.15 ± 11.33 0.025d
 FVC (L, M ± SD) 4.15 ± 0.69 4.05 ± 0.52 0.039d
 FVC % predicted (%, M ± SD) 102.18 ± 12.76 99.06 ± 10.89 0.040d
 FEV1/FVC (%, M ± SD) 87.71 ± 5.41 87.38 ± 5.18 0.78d
 MMF (L/s, M ± SD) 4.30 ± 1.00 4.15 ± 0.87 0.26d
 MMF % predicted (%, M ± SD) 91.34 ± 20.08 87.88 ± 21.45 0.32d
 FEF25 (L/s, M ± SD) 7.22 ± 1.45 6.67 ± 1.19 0.010d
 FEF25 percent predicted (%, M ± SD) 89.02 ± 17.73 81.79 ± 15.03 0.010d
 FEF50 (L/s, M ± SD) 4.97 ± 1.29 4.74 ± 1.02 0.165d
 FEF50 percent predicted (%, M ± SD) 87.07 ± 21.51 82.75 ± 18.99 0.186d
 FEF75 (L/s, M ± SD) 2.25 ± 0.74 2.17 ± 0.69 0.444d
 FEF75 percent predicted (%, M ± SD) 78.09 ± 24.34 75.49 ± 26.81 0.580d
  1. Definition of abbreviations: BMI body mass index, CCAM carbon content in airway macrophage, DET diesel engine tester, FEV1 forced expiratory volume in 1 s, FEF25 Forced expiratory flow rate at 25% vital capacity, FEF50 Forced expiratory flow rate at 50% vital capacity, FEF75 Forced expiratory flow rate at 75% vital capacity, FVC forced vital capacity, GGO ground glass opacity, GSD geometric standard deviation,; GSM geometrical mean, L/S liters per second, M mean, Mdn median, MMF maximal mid-expiratory flow, NC not calculated, PM2.5 fine particulate matter, Q1 lower quartile, Q3 upper quartile, SD standard deviation
  2. a Student t-test
  3. b Chi-square test. Fisher exact test was used for Coughing for ≥3 mo, Phlegm for ≥3 mo, Emphysema, Pulmonary fibrosis, and GGO
  4. c Wilcoxon rank sum test
  5. d Generalized linear model assessed the differences of spirometry between non-DETs and DETs with adjustment of age, height, BMI, and smoking history