TABLE 1 Baseline characteristics of participants across the four groups of airflow limitation (AL)# and asthma
TotalAL−/asthma−AL−/asthma+AL+/asthma−AL+/asthma+p-value
Subjects2121 (100)1645 (78)165 (8)237 (11)74 (3)
Males925 (44)692 (42)66 (40)124 (52)43 (58)0.001
Age years50±1849±1846±1860±1559±14<0.001
BMI+0.001
 Normal 18.5–25 kg·m−21140 (56)902 (57)76 (48)129 (57)33 (45)
 Underweight <18.5 kg·m−260 (3)42 (3)1 (1)14 (6)3 (4)
 Overweight 25–30 kg·m−2694 (34)532 (33)60 (38)69 (31)33 (45)
 Obese ⩾30 kg·m−2153 (7)114 (7)21 (13)14 (6)4 (5)
Education for >12 years913 (43)733 (45)78 (47)78 (33)24 (32)0.001
Smoking status§<0.001
 Never-smoker868 (41)737 (45)64 (39)45 (19)22 (30)
 Former smoker519 (24)357 (22)45 (27)85 (36)32 (43)
 Current smoker733 (35)550 (33)56 (34)107 (45)20 (27)
Pack-yearsƒ26±2423±2121±2240±2839±29<0.001
FEV1 % predicted93±2098±1789±1773±2259±24<0.001
Positive skin-prick tests##744 (36)552 (34)101 (64)61 (26)30 (43)<0.001
Eosinophilia¶¶135 (8)86 (7)18 (14)17 (9)14 (23)<0.001
IgE IU·mL−1++28 (26–30)24 (22–26)86 (66–111)27 (21–33)82 (54–125)<0.001
Self-reported COPD§§318 (15)143 (9)57 (35)69 (30)49 (66)<0.001
Deceased by January 1, 20111367 (64)994 (60)97 (59)209 (88)67 (91)<0.001
  • Data are presented as n (%), mean±sd or geometric mean (95% confidence interval), unless otherwise stated. BMI: body mass index; FEV1: forced expiratory volume in 1 s; COPD: chronic obstructive pulmonary disease. #: defined as FEV1/forced vital capacity <70%; : p-values are from ANOVA for continuous variables or Pearson Chi-squared test for categorical variables across the four groups; +: n=2047; §: n=2120; ƒ: only calculated among 1250 smokers; ##: n=2084; ¶¶: n=1600; ++: n=1903; §§: defined as a self-report of having been seen by a doctor for chronic bronchitis and/or emphysema (n=2111).