The evaluation of lung function in rural dwelling children

Abstract

Background: Asthma severity indicators and their risk factors are understudied in the farming and non-farming populations. Further study is needed. Our objective was to evaluate rural exposures and pulmonary function in a rural pediatric population and their relationships. Methods: For this study, data from the Saskatchewan Rural Health Study (SRHS) child component was used. SRHS is a population-based study, conducted in 2011, evaluating the health of rural dwelling residents in the province of Saskatchewan, Canada. The SRHS is designed as a cohort study. However, the data used for this analysis is from the baseline data collection. The initial data collected included a parent-completed survey questionnaire answered on behalf of the child. From this study sample, a subset of children (6-14 years old) was selected to participate in clinical testing, which included anthropometric measures and pulmonary function testing (PFT) using spirometry (n=584). PFTs followed ATS criteria and all statistical analyses were controlled for child age, sex, and height. Results: Among children participating in the clinical testing, 47.5% were female and 54.5% lived on a farm. Of those living on farms, 77.5% were livestock farms. The mean percent predicted value (PPV) for Forced Expiratory Volume in 1 second (FEV1) and forced vital capacity (FVC) among those living on the farm were 104.8% and 105.4%, respectively while the mean PPV for FEV1 and FVC among the non-farm dwellers were 102.7% and 101.4%, respectively. After adjustment for potential confounders using linear regression, higher FEV1 (p=0.03) and FVC (p=0.006) were seen among farm dwelling children while there was a trend towards lower FEV1/FVC ratio (p=0.09) among farm dwellers compared to non-farm dwellers. Higher FVC and lower FEV1/FVC ratio were also seen with children who regularly emptied grain bins (p<0.05). Trends towards a higher FEV1 (p=0.14) and FVC (p=0.08) were also seen with children living on a farm in the first year of life. Conclusion: Differences in lung function were seen between farm and non-farm rural dwelling children and certain farming activities, specifically, emptying grain bins. Despite a higher FEV1 and FVC among farm dwellers, the FEV1/FVC ratio was lower compared to non-farm dwellers. A trend towards a higher FEV1 and FVC was also seen with living on a farm in the first year of life suggesting that differences in lung function seen in farm dwelling children may not be purely due to reverse causality.