A Fixed Effect Analysis of the Variation of Socioeconomic and Environmental Factors and Rate of Asthma Onset in Children Overtime within Regions of Québec (Canada)

Abstract

Socioeconomic conditions and exposure to air pollutants have been related to cardiorespiratory outcomes. Nonetheless, very few studies have looked at how changes in environmental and socioeconomic conditions overtime relate to changes in health outcomes.We assessed the relationships between the changes in environmental and socioeconomic conditions and change in asthma onset in children <13 years within small geographic units of Québec (i.e. census tracts or local health regions called CLSC) using an ecological longitudinal design. We used univariate and multivariate fixed effects negative binomial models with the population of children aged 0-14 years per geographical area as an offset to assess associations. New cases of asthma were identified from linked medico-administrative databases using a validated algorithm. For the 1386 areas, we computed for the years 2002 to 2011, the median income from the Census, the average regional background of fine particulate levels (PM2.5) estimated with ground and satellite information, the reported industrial air pollutant emissions of PM2.5 and sulfur dioxide (SO2). We also used environmental tobacco smoke (ETS) information from the Canadian CCHS survey for 18 health regions to estimate exposure of children to environmental tobacco smoke (ETS) for the years 2002 to 2011.From a multivariate model, there was a 4.21% increase in the rate of asthma onset per change of 1 ug/m3 of regional PM2.5 levels (95%CI: 3.3-5.0), and 2.88% increase per change of 1 percent of ETS (95%CI: 2.6-3.1) within studied areas. In this model, median income and industrial emissions were not significantly related to the rate of asthma onset. Our findings suggest that small area changes in regional PM2.5 levels and in ETS, which have both decreased over the years, are associated with improvements in asthma outcomes in Québec.