Gender (% females) | 88.5 | 78.1 | 0.02 | 91.0 | 78.0 | 0.007 |
Age (y), mean (SD) | 17.0 (1.0) | 17.4 (1.7) | 0.006 | 16.7 (1.0) | 17.0 (0.8) | 0.05 |
Smoking habits |
Non-smoker (%) | 50.8 | 34.0 | 0.005 | 63.5 | 59.3 | 0.56 |
Current or ex-smoker (%) | 49.2 | 66.0 | | 32.3 | 40.7 | |
Cig/day, mean (SD) | 8.8 (6.4) | 10.4 (6.8) | 0.08 | 7.6 (4.9) | 12.8 (7.3) | 0.0002 |
Atopy* (%) | 16.2 | 27.4 | 0.02 | 22.2 | 32.2 | 0.12 |
Symptoms |
Morning cough (%) | 2.1 | 3.8 | 0.39 | 4.8 | 11.9 | 0.05 |
Cough day/night (%) | 2.1 | 4.7 | 0.21 | 10.6 | 17.0 | 0.19 |
Morning sputum (%) | 0.5 | 0.9 | 0.67 | 3.2 | 6.8 | 0.22 |
Wheezing (%) | 5.8 | 14.2 | 0.01 | 16.9 | 28.8 | 0.05 |
Dyspnoea with wheezing (%) | 5.8 | 11.3 | 0.09 | 11.1 | 17.0 | 0.24 |
MHR† (%) | 24.1 | 27.4 | 0.53 | 41.3 | 47.5 | 0.40 |
Work related MHR | 1.1 | 1.9 | 0.55 | 3.2 | 3.4 | 0.93 |
Lung function tests‡ | (n=119) | (n=120) | | (n=76) | (n=48) | |
% FVC, mean (SD) | 104.4 (10.8) | 100.9 (12.5) | 0.02 | 100.3 (14.2) | 101.4 (14.0) | 0.67 |
% FEV1, mean (SD) | 105.1 (10.6) | 101.1 (12.4) | 0.008 | 100.3 (12.6) | 99.5 (13.5) | 0.72 |
FEV1/FVC, mean (SD) | 89.7 (5.4) | 88.9 (5.8) | 0.26 | 89.3 (5.9) | 87.3 (5.1) | 0.04 |
%FEF25–75%, mean (SD) | 102.5 (20.7) | 98.6 (21.2) | 0.16 | 97.8 (21.2) | 92.6 (18.1) | 0.16 |
Methacholine challenge |
BHR (15% decrease in FEV1) (%) | 33.1 | 33.8 | 0.92 | 31.9 | 31.8 | 0.99 |
log(methacholine slope§ + 0.02), mean (SD) | −1.53 (0.22) | −1.50 (0.24) | 0.35 | −1.50 (0.29) | −1.51 (0.20) | 0.81 |