Table 1—

Distribution of baseline characteristics and their relationship to the prevalence of ever-asthma

CharacteristicsSubjects n (%)Prevalence of ever-asthma
%p-value#
Age group yrs
 5–7917 (35.5)17.1
 8–91257 (49.1)18.90.25
 10–11372 (14.7)21.0
 Unknown21 (0.8)
Sex
 Male1235 (48.2)22.0
 Female1325 (51.8)15.30.0001
History of breastfeeding
 Yes1225 (59.6)15.3
 No791 (38.5)24.20.0001
 Unknown38 (1.9)0.0
Birth weight kg
 ≥2.51840 (92.1)19.2
 <2.5158 (7.9)23.30.22
Parents' education
 Secondary school or lower565 (68.4)23.20.001
 A levels or higher261 (31.6)13.4
Family history of asthma
 Yes690 (27.0)32.5
 No1836 (71.8)13.50.0001
 Unknown30 (1.2)13.3
Number of siblings aged <16 yrs
 None392 (16.2)19.9
 1955 (39.4)19.40.66
 2715 (29.5)18.6
 ≥3360 (14.9)16.7
Ethnic group
 White British1421 (58.9)21.60.0001
 Other British341 (14.1)19.4
 Other649 (26.9)11.9
Exposure to tobacco smoke
 Yes1021 (40.2)22.40.0001
 No1517 (59.8)16.0
  • #: calculated for difference in prevalence between groups using Chi-squared tests.