TABLE 2 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)1667 (79)163 (8)215 (10)76 (4)
Males925 (44)717 (43)67 (41)99 (46)42 (55)0.146
Age years50±1849±1848±1854±1855±17<0.001
BMI+<0.001
 Normal 18.5–25 kg·m−21140 (56)905 (56)72 (46)126 (63)37 (49)
 Underweight <18.5 kg·m−260 (3)42 (3)1 (1)14 (7)3 (4)
 Overweight 25–30 kg·m−2694 (34)551 (34)66 (42)50 (25)27 (36)
 Obese ⩾30 kg·m−2153 (7)117 (7)17 (11)11 (5)8 (11)
Education for >12 years913 (43)738 (44)73 (45)73 (34)29 (38)0.027
Smoking status§<0.001
 Never-smoker868 (41)746 (45)65 (40)36 (17)21 (28)
 Former smoker519 (24)374 (22)46 (28)68 (32)31 (41)
 Current smoker733 (35)546 (33)52 (32)111 (52)24 (32)
Pack-yearsƒ26±2424±2224±2335±2833±29<0.001
FEV1 % predicted93±2098±1789±1772±2260±24<0.001
Positive skin-prick tests##744 (36)544 (33)99 (63)69 (32)32 (44)<0.001
Eosinophilia¶¶135 (8)87 (7)17 (14)16 (10)15 (24)<0.001
IgE IU·mL−1++28 (26–30)23 (21–25)83 (64–108)30 (24–38)87 (58–132)<0.001
Self-reported COPD§§318 (15)146 (9)55 (34)66 (31)51 (67)<0.001
Deceased by January 1, 20111367 (64)1037 (62)103 (63)166 (77)61 (80)<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 less than the lower limit of normal; : 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).