Table 1 Baseline characteristics of apprentices recruited in the cohort
Participants at follow-up (n = 298, 78.5%)Subjects lost to follow-up (n = 87, 21.5%)
Sex, n, F/M28/27010/77
Age, mean (SD)23.49 (7.7)22.80 (7.1)
Smoking (S + Ex-S vs NS), n (%)157 (52.7)54 (62.1)
Atopy*, n (%)104 (34.9)26 (30.0)
Asthma diagnosed by a physician, n (%)56 (18.8)16 (18.4)
Probable asthma†, n (%)22 (7.4)8 (10.9)
Past exposure‡, n (%)14 (4.6)2 (1.7)
Non-work-related respiratory symptoms, n (%)49 (16.4)18 (20.5)
Non-work-related rhinoconjunctivitis symptoms, n (%)101 (33.9)33 (38.3)
PC20 ⩽16 mg/ml, n (%)57 (19.1)22 (25.2)
FEV1 ⩽80% predicted, n (%)20 (6.7)6 (6.9)
School
    A11 (3.7)5
    B102 (34.2)29
    C41 (13.8)24
    D53 (17.8)8
    E51 (17.1)7
    F5 (1.7)2
    G35 (11.7)12
  • *Atopy: a positive reaction to at least two skin-prick tests from a battery of 11 common aeroallergens; †probable asthma: ⩾2 symptoms suggestive of asthma and a PC20 ⩽16 mg/ml; ‡past exposure = contact ⩽3 months with isocyanates and without contact in the last 2 months (not meeting the exclusion criteria).

  • FEV1, forced expiratory volume in one second; PC20, provocative concentration causing a 20% decrease in FEV1; S, smoker; Ex-S, ex-smoker; NS, non-smoker.