Table. 1—

1 General characteristics of the study population

High-risk childrenLow-risk children
Subjects n274155
Sex % males5252
Age yrs4.06±0.22#4.14±0.21
Height m1.06±0.041.06±0.04
Weight kg18±318±2
Study region %
Education of the mother %
Exposure to ETS at 4 yrs %2226
Exposure to pets at 4 yrs %4748
Contact with siblings at 4 yrs %78#87
Contact with other children (no siblings) at 4 yrs %9491
LRTI at 4 yrs %1210
Symptoms of cold 2 weeks before NO+ %4543
Use of inhaled corticosteroids at 4 yrs %97
  • Data are presented as mean±sd or %, unless otherwise stated. ETS: environmental tobacco smoke; LRTI: lower respiratory tract infections (bronchitis, pneumonia, pertussis). #: p<0.05 as compared with low-risk children; : p<0.10 as compared with low-risk children; +: fever, cough, wheeze, shortness of breath, tightness of chest, coughing up phlegm.