The associations between childhood asthma and atopy, and parental asthma, hay fever and smoking

Summary. The aim of this analysis was to examine the degree to which a life time prevalence of asthma in a 7-year-old child is statistically associated with atopic conditions of the child, and with parental asthma, hay fever and smoking. In 1968, 8585 children who were born in 1961 and who were attending school in Tasmania were surveyed. This comprised 99% of the eligible population. The prevalence of a history of asthma in the 7-year-olds was 16.2% (males 19.0%, females 13.2%). Multiple logistic regression analysis showed that a history of asthma in a 7-year-old was associated with the child being male (odds ratio [OR] 1.56; 99% confidence interval 1.30–1.86), having a history of hay fever (3.86; 3.12–4.78), eczema (2.04; 1.63–2.55), hives (1.34; 1.09–1.65) or allergy to foods or medicines (1.70; 1.26–2.30), the child's mother or father having a history of asthma (2.63; 2.08–3.31 or 2.52; 1.99–3.19, respectively), and the mother being a smoker (1.26; 1.05–1.51). Parental hay fever and paternal smoking were not independently associated with childhood asthma. The strength of association between childhood asthma and parental asthma was independent of the sex of either the parent or the child, and of atopic conditions in the child. In the 133 children for whom both parents were asthmatic, 65 (49%) had a history of asthma. These findings, based on a population survey, are consistent, not only with a childhood history of asthma being strongly associated with atopy, but also with the existence of strong unmeasured determinants common to family members, the effects of which are not mediated via atopy. The risk for asthma being independent of both the sex of the child and of the parent, is consistent with a genetic aetiology for susceptibility to asthma.