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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

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

   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    
  1. LNN: lower limit of normal; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; Δ: change;
  2. * 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
  3. Fixed: FEV1/FVC < 0.70; LLN based on Swanney prediction equations [6]