Table 1

 Clinical characteristics

n = 111
FEV1, forced expiratory volume in 1 s; IVC, inspiratory vital capacity; PC20 methacholine, provocative concentration of methacholine causing a decrease in FEV1 of 20%; % pred, percentage of predicted value; Postbd, postbronchodilator.
*Median (25th–75th centile).
Data are mean (SD) unless otherwise specified.
Male:female96:15
Age (years)61.5 (7.7)
Current smokers, n (%)69 (62)
Smoking history (pack-years)*42.0 (31.3–54.5)
FEV1 (% pred)56.4 (9.8)
FEV1/IVC (%)49.9 (8.5)
Postbd FEV1 (% pred)63.2 (8.8)
Postbd FEV1/IVC (%)50.7 (8.5)
PC20 methacholine (mg/ml)*0.5 (0.2–2.4)