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 4 Association between wall area percent and spirometry in all study subjects (n = 154)^a

Wall area percent	Spirometry	β	SE	P
6th generation (%)	FEV1 (L/S)	−0.011	0.004	0.005
	FVC (L)	−0.005	0.004	0.254
	FEV1/FVC (%)	−0.147	0.050	0.004
	MMF (L/S)	−0.031	0.008	< 0.001
	PEF (L/S)	−0.005	0.013	0.709
	FEF25 (L/s)	−0.018	0.013	0.168
	FEF50 (L/s)	−0.033	0.011	0.003
	FEF75 (L/s)	−0.024	0.006	< 0.001
9th generation (%)	FEV1 (L/S)	−0.006	0.003	0.040
	FVC (L)	−0.001	0.003	0.754
	FEV1/FVC (%)	−0.110	0.036	0.003
	MMF (L/S)	−0.022	0.006	< 0.001
	PEF (L/S)	−0.005	0.009	0.639
	FEF25 (L/s)	−0.016	0.009	0.094
	FEF50 (L/s)	−0.025	0.008	0.002
	FEF75 (L/s)	−0.015	0.005	0.001

Definition of abbreviations: 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, FEV1 forced expiratory volume in 1 s, FVC forced vital capacity, L/S liters per second, MMF maximal mid-expiratory flow, PEF peak expiratory flow, SE standard error
^a Generalized linear model assessed the associations of spirometry as outcome with average wall area percent with adjustment of age, height, BMI, smoking history. β is calculated per 1% increase in average wall area percent

ISSN: 1743-8977