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Table 2 The effect of diesel exhaust exposure on wall area percent in all study subjects (n = 154)a

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 (n = 76) DET (n = 78) Ratio (95CI%) P
6th wall area percent (%)
 LB1 + 2 54.1 (45.5, 63.9) 57.4 (50.3, 64.8)   
 LB9 51.1 (42.8, 59.4) 56.0 (48.2, 62.8)   
 RB9 55.3 (46.2, 61.3) 56.4 (49.5, 63.5)   
 RB1 53.9 (43.7, 63.6) 57.0 (50.8, 64.3)   
 All 52.0 (49.9, 54.3) 55.4 (53.0, 58.0) 1.07 (1.01, 1.13) 0.031
9th wall area percent (%)
 LB1 + 2 41.6 (34.0, 51.4) 45.1 (35.4, 54.4)   
 LB9 43.6 (29.9, 54.7) 45.1 (33.6, 55.0)   
 RB9 46.5 (33.8, 56.4) 42.2 (31.0, 56.7)   
 RB1 45.8 (37.2, 58.9) 46.6 (38.6, 57.6)   
 All 43.6 (40.7, 46.6) 44.2 (41.2, 47.5) 1.02 (0.93, 1.11) 0.744
  1. Definition of abbreviations: CI confidence interval, DET diesel engine testers, LB left bronchus, RB right bronchus
  2. a Linear mixed effects model assessed differences of natural log transformed 6th and 9th wall area percent between non-DETs and DETs with adjustment of age, BMI, smoking history, CT reconstruction method, and lung lobes. Indices were shown as median (Q1, Q3). Ratio = eβ, 95%CI = e(β ± 1.96 × Se). Descriptive statistics for all were exponentials of least square means and 95%CIs that were calculated based on natural log transformed data using linear mixed effects model with adjustment for covariates listed above and may be regarded as an overall level of wall area percent based on the four sampled airways of 6th or 9th generations