Table 1

Patient characteristics

Variable Participants1-150(n = 1155) Refusals1-151
(n = 34)
Mean (SD) FEV1 (% predicted)96.4 (14.6)96.1 (17.5)
FEV1 reversibility (%)1-152 3.3 (4.1)
Sex (% female)55.361.8
Mean (SD) age (years)43.2 (11.8)45.2 (13.4)
Childhood eczema (%)1-154 11.46.1
Current smokers (%)3739
Ever smokers (%)7071
  • FEV1 = forced expiratory volume in one second.

  • 1-150 Subjects (n = 1155) who participated in the study. Initially 1988 were sampled, 239 were excluded (known asthma or COPD, congestive heart failure, lung diseases other than asthma or COPD, life expectancy less than 11 years) and 594 refused or did not respond.

  • 1-151 Random sample of subjects (34 of 594) who refused to participate at first but eventually agreed to be screened at home.

  • 1-152 Reversibility in FEV1 at 15 minutes after inhalation of 800 μg salbutamol; not assessed in subjects screened at home (as this was an important reason for refusing to participate).

  • 1-154 Percentage of affirmative answers to questionnaire question: “Did you ever experience eczema in childhood?”