Table 2

 Frequency of bronchial hyperresponsiveness (BHR) according to potential confounding factors

All(n = 5158)Men(n = 2628)Women(n = 2530)
BMI, body mass index.
Values are shown as percentage with BHR.
*For difference between groups using χ2 test.
Age
    <40 years13.19.017.5
    40–50 years12.89.6.16.0
    >50 years13.210.116.2
    p value*0.940.760.63
Age when finished education
    ⩽16 years16.412.719.8
    17–21 years12.89.416.5
    >21 years11.88.415.4
    p value0.00240.0350.10
BMI
    <25 kg/m212.28.215.3
    25–30 kg/m212.99.419.1
    >30 kg/m216.114.218.0
    p value0.0380.0060.067
Smoking
    Never smokers12.38.315.7
    Past smokers12.610.215.6
    Moderate smokers13.09.916.0
    Heavy smokers16.811.226.7
    P value0.0370.34<0.001
Atopy
    No9.25.612.5
    Yes22.017.328.7
    P value<0.001<0.001<0.001
Asthma-like symptoms
    No8.75.512.0
    Yes26.221.032.1
    p value<0.001<0.001<0.001
Current asthma
    No10.77.314.2
    Yes55.252.657.4
    p value<0.001<0.001<0.001
Family history of asthma
    No12.39.015.9
    Yes18.213.821.7
    p value<0.0010.0130.009