Table 2– Smoking as a risk factor for bronchial hyperresponsiveness (BHR) in terms of odds ratios, univariate analysis
SubjectsPD15 ≤1.6 mgPD15 ≤0.4 mg
BHROR (95% CI)BHROR (95% CI)
Subjects292
Age started smoking
 Nonsmokers12119131
 ≥20 years4291.46 (0.60–3.55)33.03 (0.59–15.61)
 <20 years129341.92 (1.03–3.60)124.03 (1.11–14.67)
Pack-years n
 <8.5#6580.75 (0.31–1.83)10.62 (0.06–6.03)
 ≥8.5106352.65 (1.40–5.00)145.99 (1.67–21.45)
 <54540.52 (0.17–1.63)0
 5–1555121.50 (0.67–3.35)32.27 (0.44–11.62)
 >1571273.29 (1.66–6.54)128.00 (2.17–29.45)
Smoking status
 Nonsmokers12119131
 Ex-smokers75121.02 (0.47–2.25)52.81 (0.65–12.12)
 Current smokers96312.56 (1.34–4.91)104.57 (1.22–17.12)
 Smoking history ≥1 year160391.53 (0.86–2.72)154.45 (1.26–15.72)
Current smoking status
 Nonsmokers and ex-smokers19731181
 0–4 cigarettes per day36112.34 (1.05–5.25)21.38 (0.28–6.80)
 5–14 cigarettes per day29102.80 (1.19–6.60)21.74 (0.35–8.63)
 ≥15 cigarettes per day30102.66 (1.14–6.23)65.88 (1.88–18.38)
  • Data are presented as n, unless otherwise stated. PD15: provocative dose causing a 15% fall in forced expiratory volume in 1 s. #: mean of pack-years in the whole cohort, 8.5; : nonsmokers and ex-smokers, and one missing included (n = 197). Bold type represents statistical significance.