Effect modifiers of desert dust exposure to allergic symptoms – From an adjunct study of Japan Environment and Children Study (JECS) -

Abstract

Introduction: Desert dust events have been linked to health outcomes such as the exacerbation of asthma or allergic rhinitis with a subtle to clear risk elevation in epidemiological studies. It remains unknown why the estimated risk varies across studies. We investigated the effect modifiers of Asian dust to allergic symptoms in pregnant women. Methods: We conducted a cohort study for 3,327 pregnant women during spring and fall in 2011-2013 in Japan as an adjunct study of the Japan Environment & Children's Study. There, we timely acquired subjects’ daily allergic-symptom scores and behaviors such as the duration spent outside on the day by sending web-based questionnaires on some days for each participant. We estimated the odds ratio of Asian dust events for the occurrence of any allergic symptom with interaction terms for possible effect modifiers (concomitant condition of allergic diseases, serum IgE to Japanese cedar pollen (JCP), duration spent outside on the day, co-existence of pollen in the air, and etc) in the GEE logistic regression model. Results: A total of 41,020 questionnaires were sent out on the evenings of Asian dust days and control days, of which 29,434 (71.8%) were completed within the set time limit of 28 hours. Among potential effect modifiers examined, significant interaction effects were found for IgE to JCP, past history of allergic rhinitis, pollen counts in the air, and time spent outside; The OR for those who spent more than 10 minutes outside was 1.30 (95%CI: 1.20-1.40), while the same OR for those who spent less than 10 minutes outside was 1.15 (95%CI: 1.03-1.28). The OR was 1.48 (95%CI: 1.34-1.64) for those with IgE to JCP when pollen was present in the air, while the OR was 0.95 (0.71-1.28) for those with IgE to JCP when pollen was not present, and 1.02 (0.92-1.14) for those negative for IgE to JCP when pollen was present.