Table 2

Cohort characteristics of included studies by year and author
Study N Cohort Follow-up period Cohort description
Gilliland et al., 2003 [45] 3792; 4th, 7th, and 10th grade public school, asthma-free students (aged 7–18 years) Annually from 1993–1998 (4 years) or until high school graduation 288 developed asthma during follow-up; 58.1% Caucasian, 28.4% Hispanic, 4.8% Black, 5.6% Asian, 3.1% other; 24.2% overweight at baseline; 10.4% obese at baseline
Girls: N = 1993
Boys: N = 1799
Gold et al., 2003 [46] 9828; U.S. Six-City Study: children aged 6–14 years Annually from 1974–1979 (5–7 years) 90% were age 10 or younger at baseline; 3.4% of whites developed asthma with any wheeze during follow-up; 4.7% of blacks developed asthma with any wheeze during follow-up
Girls: N = 4858
Boys: N = 4970
Mamun et al., 2007 [47] 2812; Australian birth cohort of 7223 mothers and children enrolled from 1981–1984; used 2812 child participants who had complete BMI and asthma at ages 5 and 14 years Birth cohort assessed at first antenatal clinic visit between 1981–1984, 3–5 days post delivery, 6 months after birth, 5 and 14 years after birth Mean BMI at age 5 years was 20.64; 8.13% had asthma at age 5 years; 22.28% had asthma in last 6 months at age 14 years
Girls: N = 1340
Boys: N = 1472
Mannino et al., 2006 [48] 4393; U.S. Children born to women in the National Longitudinal Survey of Youth who first entered the cohort prior to age 2 years and were asthma-free at enrollment 14 years; 1986–2000; data collected every 2 years 218 developed asthma during follow-up; median age for asthma 7.6 years; 55.3% Caucasian, 25.6% Hispanic, 19.1% Black; 33.1% overweight at baseline
Girls: N = 2218
Boys: N = 2175
Zhang et al., 2010 [49] 259; High-risk full-term newborns (birthweight > 2000 g) with at least 1 asthmatic/atopic parent Nov 1998 - May 2000 56.4% male and 43.6% female; 86.8% Caucasian and 13.2% ethnic minority; 22% overweight at age 3 years
Girls: N = 112 at 6 yrs;
Boys: N = 147 at 6 yrs;
238;
Girls N = 103 at 8 yrs; Boys N = 135 at 8 yrs
Ho et al., 2011 [50] 4052; Taiwanese adolescents with pre-asthmatic symptoms selected by non-physician staff from a cohort of 9546 12 month follow-up 1995-1996 10.9% boys and 14.1% girls developed asthma during follow-up; 13.0% overweight at baseline; 12.0% obese at baseline
Girls: N = 1846
Boys: N = 2206

Egan et al.

Egan et al. BMC Pediatrics 2013 13:121   doi:10.1186/1471-2431-13-121

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