Risk factors of childhood asthma: a Sri Lankan study.

A case-control study was carried out to evaluate the genetic and environmental risk factors of childhood asthma in a group of Sri Lankan children. Three hundred cases (admitted with symptoms of asthma) and 300 age-matched controls were compared over a period of 23 months commencing in January 1996. Family history of atopy, feeding habits in infancy, bronchiolitis in infancy, passive smoking, exposure to dust and dampness, and exposure to pet animals were studied as risk factors for asthma. The risks associated with social factors were also studied. The risk associated with variables were calculated using the chi-squared test in the bivariate analysis and the forward logistic regression model in the multivariate analysis. Parental asthma, asthma in a sibling and in a relative, parental allergic rhinitis, discontinuation of breastfeeding after 6 months in infancy, bronchiolitis in infancy, living in a dusty environment, and a father with primary education compared to secondary education were independently associated with an increased risk of asthma (p < 0.05). This study reinforces the view that asthma has a multifactorial aetiology. Influence of paternal asthma is more than that of maternal asthma. As a preventive measure continuation of breastfeeding beyond 6 months is important.