Table 1

General and clinical characteristics of never-smokers according to the presence of airflow limitation and asthma at baseline

FEV1/FVC <70%FEV1/FVC ≥70%
Asthma
(n=448)
No asthma
(n=1162)
Asthma
(n=1364)
No asthma
(n=10 745)
General characteristics
 Men (%)43*3134‡33
 Age (years)64 (52–72)*69 (60–78)51 (44–62)‡58 (47–68)
 Weight (kg)75 (65–85)†73 (64–84)78 (67–88)§77 (67–89)
 BMI (kg/m2)26 (23–28)26 (23–29)26 (24–30)§27 (24–30)
 FEV1% of predicted74 (61–85)*83 (71–93)93 (85–102)‡96 (87–106)
 FVC % of predicted90 (78–102)*98 (85–108)94 (86–103)‡95 (86–104)
 FEV1/FVC (%)64 (59–67)*66 (62–68)79 (75–82)‡80 (76–83)
 Familial predisposition for asthma (%)36*2043§19
 Asthma, hay fever, or eczema in childhood (%)51*124815
 Low leisure time physical activity (%)7989
 Low education (%)26†3318‡26
 Low annual household income (%)17†2311§15
 Occupational exposure to dust and/or fumes (%)12†81310
 Daily exposure to passive smoking (%)141423‡21
Clinical characteristics
 Allergy (%)83*298533
 Use of respiratory medication (%)79*565‡2
 Duration of asthma (years)28 (12–43)NA18 (8–30)‡NA
 Respiratory symptoms
  Wheezing (%)79*277625
   During a cold (%)53605865
   During activity (%)55*315424
   Unknown situations (%)21†322230
  Dyspnoea¶ (%)68*7960§77
  Nighttime dyspnoea (%)21*7197
  mMRC ≥2 (%)222216§16
  Chest pain or tightness (%)101078
  Sputum (%)24†1719§13
  Cough (%)41*2150§22
  Any respiratory symptoms (%)100100100100
 Severity of airflow limitation
  FEV1% of predicted ≥80 (%)36*5885‡89
  ≥60 FEV1% of predicted <80 (%)40†3214‡10
  FEV1% of predicted <60 (%)24*101‡1
 Level of inflammatory biomarkers in the systemic circulation
  C reactive protein (mg/L)1.5 (1.0–2.3)1.5 (1.0–2.6)1.5 (1.0–2.6)1.5 (1.0–2.6)
  Fibrinogen (μmol/L)10.9 (9.4–13.0)11.1 (9.8–12.9)10.6 (9.3–12.5)11.0 (9.5–12.7)
  Leucocytes (×109/L)7.2 (6.2–8.4)*6.9 (5.9–8.0)7.1 (6.2–8.1)6.9 (6.0–8.1)
  Neutrophils (×109/L)4.2 (3.4–5.2)†4.0 (3.3–4.9)4.1 (3.4–4.9)§4.0 (3.3–4.9)
  Eosinophils (×109/L)0.27 (0.17–0.40)*0.17 (0.11–0.25)0.21 (0.13–0.33)‡0.16 (0.11–0.24)
  IgE** (IU/mL)77 (29–188)*26 (9–61)48 (20–104)‡23 (8–52)
  • Data are summarised as median with the 25th and 75th percentiles, or per cent.

  • *p<0.001 and †p<0.05 for comparison among individuals with airflow limitation, calculated using Pearson's χ2 test if comparing categorical data and Wilcoxon's non-parametric rank-sum test if comparing continues data.

  • ‡p<0.001 and §p<0.05 for comparison among individuals with asthma, calculated using Pearson's χ2 test if comparing categorical data and Wilcoxon's non-parametric rank-sum test if comparing continues data.

  • ¶Dyspnoea was shortness of breath during different levels of activity, at nighttime, and/or while seated/at rest.

  • **Not available for all individuals listed in the table.

  • BMI, body mass index; mMRC, modified Medical Research Council dyspnoea scale; NA, not applicable.