Genetic and environmental risk for asthma in children aged 5-11 years

Objective To assess genetic and environmental risk factors of asthma among children aged 5-11 years.

Design A cross sectional analytical study.

Method Data were collected from children aged 5-11 years in 3 schools in Gampaha District. 441 children with asthma and 1510 without asthma were evaluated for following risk factors viz. family history of atopy, gender, duration of breast feeding, commencement of formula in infancy, dusty home environment, passive indoor cigarette smoking, presence of firewood smoke in bedroom when cooking, burning of mosquito coil and incense stick/powder and presence of pets at home. Data were analyzed using Epi info version 6 and SPSS package. Chi Squared test was used in bivariate analysis and forward logistic regression was used to adjust confounding factors.

Results Risk of asthma in child (on bivariate analysis) was increased when father has a history of asthma (odds ratio (OR) 6.4 (95% confidence interval (CI) 3.2 -13.2), mother has a history of asthma (OR 4.4, CI 2.6 -7.5), sibling has asthma (OR 4.3, CI 2.0 - 9.7), father has a history of allergic rhinitis (OR 2.0, CI 1.5-2.8), mother has a history of allergic rhinitis (OR 2.5, CI 1.9-3.4) and sibling has allergic rhinitis (OR 3.4, CI 2.1-5.4). Asthma risk was significantly increased with following environmental factors: non continuation of breast feeding beyond first 6 months in infancy (OR 1.5, CI 1.2-1.9), presence of firewood smoke in bedroom when cooking (OR 1.4, CI 1.1- 1.9), use of mosquito coil (OR 1.5, CI 1.2 -1.9) and dusty home environment (OR 1.8, CI 1.4-2.3). After adjusting for confounding factors, paternal history of asthma, maternal history of asthma, allergic rhinitis in mother and sibling, non continuation of breastfeeding beyond first 6 months of life and dusty environment remained significant with increased risk of asthma (p < 0.01).

Conclusions This study reinforces that asthma has a multifactorial aetiology. Childhood asthma is influenced by paternal asthma more than maternal asthma. Significant modifiable environmental factors in this study were duration of breastfeeding in infancy and dusty home environment

Key words: genetic risk, environmental risk, asthma, children

doi: 10.4038/sljch.v34i3.398

Sri Lanka Journal of Child Health, 2004; 34:79-83