Parental Stress, Traffic, and New Onset Asthma in a Cohort of Children

Abstract

SM4-PD-10 Recent literature suggests that both traffic-related pollutant exposure and psychosocial stress are risk factors for childhood asthma. However, there has been little study of synergistic effects or of associations of these risk factors with new onset asthma in prospective studies. We examined the relationship of local traffic-related exposure and of parental stress to the risk of incident asthma in the southern California Children's Health Study. A cohort of 5- to 7-year-old children was recruited in 2003, and a parent of each child completed a questionnaire on the child's history and symptoms of asthma and relevant risk factors. Parental stress at study entry was assessed using a well-validated 4-question perceived stress scale. The child's residential exposure was assessed by modeling exposure to local traffic-related pollutants. A yearly parent-completed questionnaire identified children with new-onset asthma through 2005. The relative risk of new onset childhood asthma associated with parental stress was 1.19 over the interquartile range of stress in the study population (95% CI, 1.00–1.41). There was no association of incident asthma with traffic modeled pollution by itself, but there was a significant interaction of parental stress with the child's residential traffic exposure. The relative risk of asthma associated with the interquartile range of traffic-modeled pollutant exposure was 2.48 (1.37–4.50) among children with parents in the upper quartile of perceived stress. The pattern of effects was similar among children with no lifetime history of wheeze at study entry, indicating that the associations with incident asthma did not merely reflect exacerbation of preexisting (but undiagnosed) asthma. These results suggest that parental stress may make children more susceptible to traffic-related asthma.