Table 1

Characteristics of cohort participants with Irreversible airflow limitation or Reversible airflow limitation and normal lung function*

Irreversible airflow limitation (N=39)Reversible airflow limitation (N=103)Normal lung function (N=1790)P value
Irreversible airflow limitation versus normal lung functionReversible airflow limitation versus normal lung function
Age, years, mean (SD)22.4 (0.5)22.4 (0.5)22.4 (0.5)0.73870.5593
Sex, female, n (%)19 (48.7)58 (56.3)1042 (58.2)0.23460.7037
BMI, kg/m2, mean (SD)24.9 (5.9)23.2 (3.0)23.1 (3.8)0.00600.9549
Education, n (%)0.15060.7524
 Secondary school20 (51.3)62 (60.2)1118 (62.6)
 High school9 (23.1)23 (22.3)405 (22.7)
 University10 (25.6)18 (17.5)264 (14.8)
Active childhood smoking, n (%)0.28040.8711
 Never23 (59.0)70 (68.0)1200 (67.2)
 Ever16 (41.0)33 (32.0)586 (32.8)
Tobacco consumption (pack-years), median (IQR)1.1 (0.1 to 1.6)1.0 (0.1 to 2.3)0.4 (0.1 to 1.7)0.4504 0.3609
Respiratory health events
 Cough during winter morning, n (%)9 (23.1)11 (10.8)139 (7.9)0.00060.3686
 Mucus production during winter morning, n (%)6 (15.8)18 (17.8)257 (14.6)0.83190.4999
 Respiratory symptoms, n (%)19 (48.7)34 (33.0)451 (25.2)0.00090.0791
 Pneumonia in the last 12 months, n (%)4 (10.3)3 (3.0)44 (2.5)0.0183‡0.7387‡
Sensitisation at age 24 years
 Sensitisation to airborne allergens, n (%)18 (46.2)36 (35.6)767 (43.5)0.74140.1207
 Sensitisation to food allergens, n (%)5 (12.8)10 (9.9)153 (8.7)0.3826‡0.6736
Reversibility test
 Change in FEV1, ml, median (IQR)243 (156 to 360)273 (192 to 373)111 (50 to 185)<0.0001<0.0001
 Change in FEV1 % baseline, %, median (IQR)7.3 (4.2 to 10.2)7.7 (5.1 to 9.9)2.8 (1.3 to 4.6)<0.0001<0.0001
Blood different cell count, ×109/L
 Neutrophils, mean (SD)3.86 (1.5)3.51 (1.37)3.71 (1.4)0.53580.1734
 Eosinophils, median (IQR)0.10 (0.1 to 0.2)0.10 (0.0 to 0.2)0.10 (0.0 to 0.2)0.05290.7534
  • *Details about the definitions of health outcomes and covariates are provided in the online supplemental file.

  • †Based on Kruskal-Wallis rank sum test.

  • ‡Based on Fisher’s exact test.

  • BMI, body mass index; FEV1, forced expiratory volume in 1 s.