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Asthma phenotypes modify the impact of environmetnal factors on lung function
Citation:
NEAS, L. M. Asthma phenotypes modify the impact of environmetnal factors on lung function. Presented at International Society for Environmetnal Epidemiology, Dublin, Northern Ireland, IRELAND, September 25 - 29, 2009.
Impact/Purpose:
research results
Description:
Previous studies have examined the role of childhood asthma phenotypes based on clinical history on asthma severity and symptom aggravation by environmental risk factors. The current study focuses on the associations between lung function in childhood and environmental factors and the modification ofthese factors by asthma phenotypes. Methods: From a case-cohort sample of inner-city children aged 7 to 13 years selected from the administrative records of a large health maintenance organization, we obtained acceptable pulmonary function and exhaled nitric oxide measurements from 615 children who were divided into three phenotypes: 349 children who had never had asthma (never asthma), 189 children who had an asthma-related clinical visit in the last 2 years (current asthma), and 77 children who had some prior history of asthma, but who had no asthma-related clinical visit in the last 2 years (former asthma). Results: The former asthma children showed strong decrements in forced expiratory flow at one second (FEVl) associated with early-life exposures to tobacco smoke: smoking during pregnancy (-7.2%,95% CI -13.7%, -0.1%) and environmental tobacco smoke before age two (-8.0%,95% CI -14.1, -0.2%). The current asthma children showed FEVI decrements associated with indoor combustion sources: gas stoves with pilot lights (-4.9%, 95% CI -10.1, 0.03) and non-gas/non-electric heat (-12.4%, 95% CI -20.9, -0.4%). In both cases, these environmental factors were not significantly associated with pulmonary function decrements among the other two phenotypes. Conclusion: The delineation of distinct asthma phenotypes is essential to the assessment ofthe physiologic impact of environmental risk factors in childhood asthma.