Characteristics Total Total Cohort 1 Cohort 1 Cohort 2 Cohort 2 P value§
N 5965 5965 3233 3233 2732 2732
Age, yrs 12.45 0.42 12.70 0.34 12.15 0.30 <0.001
Male sex 3043 51.01 1669 51.62 1374 50.29 0.31
Breast Feeding 2480 49.50 1561 48.28 919 51.72 0.02
Parental Education
High school or below 3440 57.67 2085 64.49 1355 49.60 <0.001
College or university 2163 36.26 1026 31.74 1137 41.62
Post-graduate school 362 6.07 122 3.77 240 8.78
Family income (USD)
<20,000 3274 54.89 2021 62.51 1253 45.86 <0.001
20,001-330,000 1827 30.63 848 26.23 979 35.83
>330,001 864 14.48 364 11.26 500 18.30
Household cigarette smoke 2577 43.20 1525 47.17 1052 38.51 <0.001
BMI (kg/m2) at age 12 20.49 4.16 20.57 4.23 20.40 4.06 0.11
Active Asthma 233 3.91 127 3.93 106 3.28 0.54