TABLE 1

Characteristics of the study population

CharacteristicsCohortNon-asthmaticAsthmaticMean difference (95% CI)OR (95% CI)p-value
Subjects n24514996
Demographics
 Age years35.8±4.835.8±4.835.7±4.9−0.06 (−1.30–1.18)0.925
 BMI kg·m−223.8±4.424.0±4.523.5±4.1−0.45 (−1.57–0.67)0.427
 FEV1 L3.12±0.43.21±0.42.98±0.4−0.24 (−0.35–−0.13)<0.001
 FEV1# % pred97.1±0.05100.2±0.0592.5±0.06−0.04 (−0.05–0.02)<0.001
 FEV1/FVC# %80.9±0.0782.0±0.0379.2±0.11−0.02 (−0.03–0.003)0.109
 Former smoker %112 (45.9)63 (42.3)49 (51.0)1.42 (0.85–2.38)0.191
 Single/lesbian in population %38 (15.5)26 (17.4)12 (12.5)0.68 (0.32–1.41)0.367
Asthma markers
 Log FeNO+ ppb1.05±0.31.03±0.21.09±0.30.06 (−0.01–0.12)0.093
 Allergy99 (40.4)39 (26.2)60 (62.5)4.70 (2.71–8.16)<0.001
 Log RDR methacholine0.25±0.7−0.08±0.50.73±0.70.82 (0.67–0.97)<0.001
 % AHR to methacholine35.910.1ƒ76.0
 Log RDR mannitol§−1.64±0.8−1.56±0.8−2.21±0.50.65 (0.11–1.15)0.012
 % AHR to mannitol§34.6041.4
 ACQ score0.21±0.40.07±0.10.43±0.50.36 (0.28–0.45)<0.001
Serum IL levels
 IL-6, pg·mL−11.22±1.41.19±1.51.26±1.30.07 (−0.28–0.43)0.694
 hsCRP mg·L−11.90±4.91.603±3.02.33±7.00.70 (−0.57–1.98)0.276
 TNF pg·mL−10.82±0.60.79±0.60.85±0.70.05 (−0.10–0.21)0.502
 IL-8 pg·mL−14.29±3.04.18±2.04.47±4.00.29 (−0.47–1.06)0.447
 IL-10 pg·mL−10.19±0.40.18±0.40.20±0.40.05 (−0.09–0.12)0.720
 Log ECP μg·L−10.94±0.40.90±0.41.0±0.30.09 (0.00–0.18)0.049
 Log IgE kU·L−11.35±0.61.20±0.51.60±0.60.40 (0.26–0.54)<0.001
Fertility treatment mean %
 Stimulated cycles0.47 (1.5)0.34 (1.2)0.68 (1.7)0.33 (−0.04–0.71)0.081
 IUI4.7 (3.9)4.7 (3.8)4.8 (4.0)0.16 (−0.85–1.16)0.762
 IVF2.87 (3.4)2.73 (3.1)3.10 (3.8)0.36 (−0.51–1.24)0.415
 ICSI0.34 (1.4)0.32 (1.3)0.37 (1.5)0.04 (−0.31–0.40)0.813
 Donor oocyte0.05 (0.28)0.06 (0.3)0.02 (0.1)−0.04 (−0.11–0.03)0.273
  • Data are presented as mean±sd or n (%) unless otherwise stated. Data in bold is statistically significant. BMI: body mass index; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; FeNO: fractional exhaled nitric oxide; RDR: response dose ratio; AHR: airway hyperresponsiveness; ACQ: asthma control questionnaire; IL: interleukin; hsCPR: high sensitivity C-reactive protein; TNF: tumour necrosis factor; ECP: eosinophil cationic protein; IUI: intrauterine insemination; IVF: in vitro fertilisation; ICSI: intra cytoplasmic sperm injection. #: p-values and mean differences were calculated in log values; : relationship was defined as single/lesbian or heterosexual; +: geometric mean; §: mannitol test was performed only on patients with AHR to methacholine. ƒ: all non-asthmatics with a post metacholine test had negative mannitol tests.