Risk factors associated with current asthma and wheeze in school children along an urban-rural gradient in Saskatchewan

Abstract

Background: The prevalence of childhood asthma varies geographically with a lower prevalence of asthma reported among rural compared to urban dwelling children. Although several explanations have been proposed, evidence is required to determine which of these explanations is most plausible. The purpose of this study was to identify the risk factors associated with current childhood asthma and wheeze and to determine which risk factors best explain the variations of asthma prevalence between urban and rural settings Methods: In 2013, we conducted a cross-sectional survey of 3,420 school children (aged 5-14 years) from three regions of Saskatchewan representing a large urban, small urban, and rural area (Regina, Prince Albert and the rural area around Prince Albert, respectively). Self-reported questionnaires were used and information was collected on lung and general health, indoor environment, health behaviors, and socio-demographics. Results: A lower prevalence of current asthma was observed in the rural area (11.5%) compared to the large urban (14.6%) and small urban areas (15.9%) but after adjustment for a large number of variables, this association was not statistically significant (OR=0.80, 95%CI=0.47-1.36). Risk factors for both current wheeze and current asthma included children with any allergy (OR=4.50, 95%CI=3.25-6.23; OR=5.00, 95%CI=3.53-7.01), parental history of asthma and allergies (OR=1.62, 95%CI=1.17-2.25; OR=2.21, 95%CI=1.56-3.12), home dampness (OR=1.91, 95%CI=1.27-2.87; OR=1.70, 95%CI=1.10-2.62), seafood consumption in the past 12 months (OR=1.64, 95%CI=1.17-2.29; OR=1.61, 95%CI=1.12-2.30). Age was a risk factor for current wheeze (OR=0.67, 95%CI=0.48-0.94) and sex showed an inverse association for current asthma (OR=0.70, 95%CI=0.50-0.99). The association between urban-rural status with current wheeze and current asthma were affected by type of fuel used for heating the home and consumption of nuts in the past 12 months although true mediation was not seen. Significant effect modification between personal and environmental risk factors with geographical location was found for both current wheeze and current asthma. Conclusions: The prevalence of asthma was lower among children living in rural areas. However, the association was not entirely consistent and mediation by various risk factors was not fully observed. Also, while there were some consistent associations with current asthma and wheeze, the association between some personal and environmental risk factors with asthma and wheeze were modified by geographic location.