Lung function decline in relation to diagnostic criteria for airflow obstruction in respiratory symptomatic subjects

Table 4 Mean (standard error) results for the primary and the secondary outcomes in the three defined categories for current smokers and non-smokers in the base case population

		Category
	Non-obstructed (n = 2,406)	Discordant (n = 389)	Obstructed (n = 529)	p-value*
	(LLN-Fixed-)	(LLN-Fixed+)	(LLN+Fixed+)	Overall difference between categories	LLN-Fixed+ versus LLN-Fixed-	LLN-Fixed+ versus LLN+Fixed+
ΔFEV1 postbronchodilator, ml/year (SE)
Smokers	-21 (3)	-21 (7)	-50 (5)	< 0.001	0.973	0.004
n	578	138	292
Non-smokers	-15 (1)	-17 (4)	-36 (4)	< 0.001	0.624	0.004
n	1828	251	237
ΔFEV1 prebronchodilator, ml/year (SE)
Smokers	-13 (3)	-13 (7)	-50 (5)	< 0.001	0.998	< 0.001
n	578	138	292
Non-smokers	-9 (2)	-14 (5)	-30 (5)	< 0.001	0.301	0.016
n	1828	251	237
ΔFVC postbronchodilator, ml/year (SE)
Smokers	-18 (5)	-17 (9)	-33 (6)	0.133	0.914	0.154
n	578	138	292
Non-smokers	-15 (2)	-18 (6)	-22 (5)	0.420	0.555	0.647
n	1828	251	237
ΔFVC prebronchodilator, ml/year (SE)
Smokers	-12 (5)	-5 (10)	-46 (7)	< 0.001	0.544	0.001
n	578	138	292
Non-smokers	-7 (2)	-15 (6)	-16 (6)	0.226	0.230	0.929
n	1828	251	237

LNN: lower limit of normal; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; Δ: change;
* between group differences were analyzed with a random coefficient regression model with random intercept and random slope and were adjusted for differences in inhaled corticosteroid use between the categories. Inhaled corticosteroid use was statistically significantly associated with lung function decline at p < 0.001 level in all regression models
Fixed: FEV₁/FVC < 0.70; LLN based on Swanney prediction equations [6]

ISSN: 1471-2466