Atopy risk among school-aged children in relation to early exposures to a farm environment: A systematic review.

BACKGROUND AND OBJECTIVES: Childhood atopy is a complex condition with both a genetic and an environmental component. This systematic review will explore the current understanding of the importance of early life exposures to a farm in the development of atopy measured by objective markers of skin prick testing, and specific IgE measurements in school age children. METHODS: A systematic review was performed. RESULTS: Among 7285 references identified, 14 studies met the inclusion criteria (13 cross-sectional studies and 1 case-control study). The results were fairly consistent in that early farm-related exposures can protect children from becoming atopic at school age. In general, there was heterogeneity in the assessment of outcomes and exposures. CONCLUSIONS: Early-life farm exposures are associated with a protective effect on childhood atopy as assessed by objective markers. Future work should focus on understanding specific farm exposures that may important in these associations between atopy and farm exposures in children.

Lung Function Decline in Farm and Nonfarm Rural Residents of Saskatchewan.

OBJECTIVE: This study aims to assess the annual changes in lung function among farm and nonfarm adult residences in rural Saskatchewan, Canada. METHODS: Data from the Saskatchewan Rural Health Study survey (2010 to 2014) among 724 adults were used. RESULTS: For forced expiratory volume in 1 second (FEV1) measurements, estimates of annual decline (in milliliters) were highest in older age male (65+ years) (Mean, SD) (-42.63, 21.16); and among old heavy smokers (-57.79, 24.30). Estimates of annual decline in forced vital capacity (FVC) were highest in current smokers without the use of natural gas (-25.78, 14.78) and among old heavy smokers (-33.88, 20.28). Living on a farm is associated with decreased FEV1 and FVC, but not statistically significant by sex and age. CONCLUSIONS: A complex mix of personal and contextual factors may affect these estimates.

Incidence and Longitudinal Changes in Prevalence of Chronic Bronchitis in Farm and Non-Farm Rural Residents of Saskatchewan.

OBJECTIVE: To assess the predictors associated with incidence and longitudinal changes in the prevalence of chronic bronchitis (CB) among farm and non-farm residents of rural Saskatchewan, Canada. METHODS: The Saskatchewan Rural Health Study was a prospective study of the lung health of rural dwellers. We obtained information on 4624 households, 8261 individuals (2797 households, 4867 individuals) at baseline (follow-up). RESULTS: Incidence of CB was 4.3% over 4 years. The prevalence was 6.4% and 5.3% (baseline) and 12.1% and 9.2% (follow-up) in non-farm and farm residents, respectively. The prevalence of CB was associated with current smokers; father ever had lung trouble; obesity; mother smoked during pregnancy; allergic reaction to cats and to pollen; household income inadequacy and age. CONCLUSION: Prevalence and incidence of CB in rural people appear to be a complex mix of personal and contextual factors.

Prevalence and associated factors for self-reported asthma in a Canadian population: The Canadian Community Health Survey, 2014.

BACKGROUND: Asthma prevalence is increasing among adults, yet limited information regarding the association between adult asthma and environmental and personal exposures is available using large nationally representative population-based survey. OBJECTIVE: To determine the prevalence of asthma and associated factors for self-reported asthma in a Canadian population aged 12 years and older by using the Canadian Community Health Survey (CCHS) 2014 cross-sectional cohort. METHODS: We used data from the 2014 CCHS. Asthma was determined through self-reported health professional diagnosis. Information regarding covariates of importance, such as socio-economic status, life style variables, was obtained. A weighted logistic regression analysis was performed with appropriate technique for clustering effects. RESULTS: Estimated self-reported asthma prevalence of 8.1% in the greater than 12 years old Canadian population was observed. We found that a substantial proportion of Canadians (aged 12 and older) reported having asthma and geographical differences and differences between specific provinces in asthma prevalence. Women had higher prevalence of asthma than men, but the relationship depended on age and body mass index (BMI). Interactions between household income and smoking status were observed to predict the probability of asthma. CONCLUSIONS: Additional studies are needed to determine which factors influence the asthma prevalence between sex, BMI as well as smoking status and household income and its interactions with each other.

Prevalence, risk factors, and clinical outcomes of atopic and nonatopic asthma among rural children.

BACKGROUND: Because of time and cost constraints, objective classification of atopic and nonatopic asthma has been limited in large epidemiologic studies. However, as we try to better understand exposure-outcome associations and ensure appropriate treatment of asthma, it is important to focus on phenotype-defined asthma classification. OBJECTIVE: To compare atopic and nonatopic asthma in rural children with regard to risk factors and clinical outcomes. METHODS: We conducted a cross-sectional study in rural Saskatchewan, Canada, in 2011. Parents of 6- to 14-year-old children completed a health and exposure survey. Skin prick tests were completed in a subsample of 529 children. Asthma was based physician diagnosis. Asthma status was defined as no asthma, nonatopic asthma, and atopic asthma. RESULTS: Asthma prevalence was 14.7% of which 32.1% of cases were atopic. After adjustment, early respiratory illness and a family history of asthma were predictors of childhood asthma, regardless of atopic status (P < .05). Being overweight and having a dog in the home were associated with an increased risk of nonatopic asthma (P < .05). A mother with a history of smoking increased the risk of atopic asthma (P = .01). Compared with those with nonatopic asthma, in the past 12 months, children with atopic asthma were more likely to report a sneezy, runny, or blocked nose or have shortness of breath (odds ratio >2), whereas those with nonatopic asthma were more likely to have parents who missed work (odd ratio >3). Those with nonatopic asthma had significantly lower forced expiratory volume in 1 second compared w2ith those with atopic asthma. CONCLUSION: Exposures may contribute differentially to atopic and nonatopic asthma and result in differential clinical presentation or burden. The study of these characteristics is important for etiologic understanding and management decisions.

Prevalence and determinants of atopy and allergic diseases among school-age children in rural Saskatchewan, Canada.

BACKGROUND: There have been few investigations of farming-related activities or specific characteristics resulting in the associations between those exposures and atopic disease. OBJECTIVE: To study the associations between farm-associated exposures and atopic diseases. METHODS: As part of a longitudinal study of lung health in rural residents, a cross-sectional baseline study was conducted in rural Saskatchewan, Canada. This included an initial survey phase followed by a clinical testing phase. A subsample of 584 children (grades 1-8) completed skin prick testing to assess atopic status. Atopy was defined as a positive reaction to any of 6 allergens (local grasses, wheat dust, cat dander, house dust mite, Alternaria species, or Cladosporium species) of at least 3 mm compared with the negative control. RESULTS: Of those who completed clinical testing, the prevalence of atopy was 19.4%, that of hay fever was 8.8%, and that of eczema was 27.4%. Based on skin prick testing, sensitization was highest for cat dander (8.6%) followed by local grasses (8.2%) and house dust mite (5.1%). After adjustment for potential confounders, home location (farm vs non-farm) was not associated with atopic status. However, livestock farming was protective against atopy (adjusted odds ratio 0.38, 95% confidence interval 0.17-0.88). In contrast, current residence on a farm was associated with an increase in the likelihood of hay fever in these children (adjusted odds ratio 3.68, 95% confidence interval 1.29-10.45). Also, regular farming activities in the past year were associated with an increased risk of hay fever. CONCLUSION: In children, livestock exposure has a protective effect on skin prick test positivity, whereas farm living and activities increase the risk of hay fever.