Table 1

 Demographic features, medication, and physiology of subjects studied

Normal subjects Asthma COPD
No. of subjects965357
Median (range) age (years)38 (20–65)51 (22–73)65 (45–88)
Sex (% male)346275
Smoking habits (%)
 Current smokers171740
 Ex-smokers204060
 Non-smokers63430
Drug treatment (%)
 β agonists0100100
 Anticholinergics0 21 83
 Theophylline0  8 19
 Inhaled corticosteroids0100 35
Lung function
 Mean (SE) FEV1 (l)3.7 (0.48)2.1 (0.12)1.1 (0.1)
 Mean (SE) FVC (l)4.4 (0.62)3.4 (0.16)2.6 (0.1)
 % Predicted FEV1 (SE)107 (14)71 (3)42 (2)
Mean (SE) PEF variability (%)15.9 (1.2)17.0 (1.8)
(n=53)(n=18)
Mean (SE) PC20(mg/ml) 1.9 (0.46)
(n=43)
  • FEV1 = forced expiratory volume in one second; FVC = forced vital capacity; PEF = peak expiratory flow; PC20 = concentration of histamine provoking a fall in FEV1 of 20% or more.

  • Values are numbers of subjects except when otherwise stated.