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Table 3 Baseline characteristics for the base case study population (categories based on Swanney prediction equations [6])

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

  Total cohort
(n = 3,324)
Non-obstructed
(n = 2,406)
Discordant
(n = 389)
Obstructed
(n = 529)
p value
   LLN*-Fixed- LLN*-Fixed+ LLN* + Fixed+  
Follow-up time, years (SD) 3.4 (1.4) 3.4 (1.4) 3.2 (1.4) 3.4 (1.5) 0.592
Males, n (%) 1,500 (45) 894 (37) 245 (63) 361 (68) < 0.001
Age, mean (SD) 58.1 (11.0) 56.2 (10.5) 67.0 (10.1) 60.3 (10.2) < 0.001
   40-49, n (%) 918 (28) 798 (33) 30 (8) 90 (17)  
   50-59, n (%) 1,003 (30) 758 (31) 66 (17) 179 (34)  
   60-69, n (%) 827 (25) 553 (23) 118 (30) 156 (29)  
   70-79, n (%) 512 (15) 277 (12) 144 (37) 91 (17)  
   > 80, n (%) 64 (2) 20 (1) 31 (8) 13 (3) < 0.001
Height, m 1.69 (0.1) 1.68 (0.1) 1.73 (0.1) 1.70 (0.1) < 0.001
BMI, kg/m [2] (SD) 27.5 (5.0) 28.2 (5.2) 27.0 (4.2) 25.0 (4.0) < 0.001
Smoking status, n (%)
   Never 956 (29) 864 (36) 59 (15) 33 (6)  
   Former 1,360 (41) 964 (40) 192 (49) 204 (39)  
   Current 1,008 (30) 578 (24) 138 (36) 292 (55) < 0.001
Respiratory medication use, n (%)
   Short-acting bronchodilators 1,436 (43) 1,061 (44) 147 (38) 228 (43) 0.066
   Long-acting bronchodilators 1,174 (35) 841 (35) 144 (37) 189 (36) 0.715
   Inhaled corticosteroids 1,972 (59) 1,550 (64) 185 (48) 237 (45) < 0.001
FEV1
   Prebronchodilator, liters (SD) 2.28 (0.74) 2.46 (0.71) 2.02 (0.65) 1.64 (0.51) < 0.001
as % predicted* (SD) 74.6 (17.9) 81.1 (14.5) 65.3 (12.1) 51.7 (12.8) < 0.001
   Postbronchodilator, liters (SD) 2.46 (0.77) 2.63 (0.74) 2.21 (0.68) 1.85 (0.56) < 0.001
as % predicted* (SD) 80.2 (17.4) 86.5 (14.1) 71.7 (12.3) 58.1 (13.2) < 0.001
FVC
   Prebronchodilator, liters (SD) 3.23 (0.95) 3.22 (0.95) 3.24 (1.03) 3.26 (0.91) 0.708
   Postbronchodilator, liters (SD) 3.35 (0.96) 3.30 (0.95) 3.43 (1.03) 3.53 (0.92) < 0.001
FEV1/FVC
   Prebronchodilator (SD) 0.71 (0.12) 0.77 (0.07) 0.63 (0.05) 0.51 (0.08) < 0.001
   Postbronchodilator (SD) 0.74 (0.12) 0.80 (0.05) 0.65 (0.03) 0.52 (0.08) < 0.001
  1. BMI: body mass index; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; LNN: lower limit of normal; SD: standard deviation
  2. * based on Swanney prediction equations [6]