Table 5 Association between EPHX1 phenotypes and asthma stratified by distance of residence from major roads
EPHX1 metabolic phenotypes by asthma phenotypesDistance of residence from a major roadp Value‡
⩾75 metres<75 metres
N*OR† (95% CI)N*OR† (95% CI)
Lifetime asthma
    Low/intermediate1540/2611.0367/621.0
    High343/721.25 (0.93 to 1.69)66/273.24 (1.75 to 6.00)0.03
Current asthma
    Low/intermediate1540/1751.0367/371.0
    High343/481.34 (0.91 to 1.96)66/162.91 (1.25 to 6.77)0.08
Early persistent asthma
    Low/intermediate1540/991.0367/221.0
    High343/231.10 (0.67 to 1.79)66/93.02 (1.09 to 8.33)0.18
Late onset asthma
    Low/intermediate1540/1291.0367/301.0
    High343/411.44 (0.98 to 2.11)66/174.85 (2.22 to 10.61)0.02
  • *Frequencies represent children with no asthma/children with asthma phenotype under study. Children with missing data on distance of residence from major road were excluded.

  • †ORs represent odds ratios for asthma outcomes associated with high EPHX1 phenotype within each stratum of residential distance from major road and were adjusted for age, sex, race/ethnicity, in utero exposure to maternal smoking, number of smokers at home, community of residence, parental education, health insurance and parental history of asthma.

  • ‡p value for the EPHX1 metabolic phenotypes by distance of residence from major road interactions were obtained from likelihood ratio tests from a non-stratified model with appropriate interaction terms and was based on 1 df.