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

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

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

Definition of abbreviations: CI confidence interval, DET diesel engine testers, LB left bronchus, RB right bronchus
^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 = e^β, 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

ISSN: 1743-8977