Table 1

Subjects’ characteristics

CharacteristicsSubjects with preserved spirometry (n=256)Subgroup that performed exercise (n=179)
Age (years)56.1±11.054.7±11.3
Female sex, n (%)232 (90.6)163 (91.1)
BMI (kg/m2)23.5±2.923.5±3.0
FEV1 (% predicted)103±12103±12
FVC (% predicted)106±12106±12
FEV1/FVC (%)77±477±4
FEV1/FVC (% predicted)98±598±4
FEF25–75 (% predicted)92±2391±21
FEF75 (% predicted)41±1643±17
TLC (% predicted)101±10101±10
RV (% predicted)93±1592±16
(RV/TLC) (%)34±634±6
(RV/TLC) (% predicted)92±1292±12
FRC (% predicted)96±1897±18
DcoSB adjusted for Hgb (% predicted)79±1079±10
mMRC Dyspnea Scale ≥1, n (%)23 (9.0)15 (8.4)
  Subjects ever experiencing shortness of breath, n (%)36 (14.1)23 (12.8)
  Subjects with cough ≥2 episodes/year, n (%)114 (44.5)73 (40.8)
  Subjects with less activity than peers, n (%)10 (3.9)5 (2.8)
  Subjects with any respiratory symptoms, n (%)129 (50.4)83 (46.4)
SHS exposure
  Ever cabin SHS exposure, n (%)161 (62.9)102 (57.0)
   Cabin SHS exposure (years)12.1±11.710.1±10.7
   Any form of non-cabin SHS exposure, n/N (%)196/210 (93.3)130/139 (93.5)
   Childhood home SHS exposure, n/N (%)133/207 (64.3)87/138 (63.0)
   Adult home SHS exposure, n/N (%)80/207 (38.6)48/138 (34.8)
   Non-airline occupational SHS exposure, n/N (%)73/198 (36.9)53/136 (38.9)
   Other SHS exposure, n/N (%)133/193 (68.9)90/130 (69.2)
  • Demographics, lung function and secondhand smoke (SHS) exposure status in subjects with preserved spirometry and the subgroup that underwent exercise testing. Other SHS exposure was defined as non-aircraft cabin SHS exposure outside the work or home environment such as in recreational public places. Data are presented as mean±SD or number of subjects with positive value for the variable (n) out of the total number of subjects (N) and percentage of subjects (%).

  • BMI, body mass index; DcoSB, single-breath diffusing capacity of carbon monoxide; FEF25–75, maximum airflow at mid-lung volume; FEF75, maximum airflow at low-lung volume; FEV1, forced expiratory volume in 1 s; FRC, functional residual capacity; FVC, forced vital capacity; Hgb, haemoglobin; mMRC, modified Medical Research Council; RV, residual volume; TLC, total lung capacity.