RESUMO
OBJECTIVE: To evaluate the effect of passive smoking and breastfeeding on the severity and age of onset of bronchial asthma. DESIGN: Cross-sectional study. SETTING: Paediatric observation ward and paediatric chest clinic, Kenyatta National Hospital. PATIENTS: Children aged between one and 120 months. RESULTS: More than fifty per cent of the children had their first wheeze at less than 12 months of age and 68% were categorised as having moderate to severe asthma. Passive smoking was positively significantly associated with early onset of wheezing (chi 2 = 6.22, p = 0.012, Odds ratio = 2.44, 95% CI 1.2,5.0), and also, at a non significant level, to severity of asthma (chi 2 = 2.8, p = 0.09, Odds ratio = 2.1, 95% CI 0.9,4.7). On the other hand, exclusive breastfeeding was significantly negatively associated with severity of bronchial asthma (chi 2 = 4.02, p = 0.045, Odds ratio = 0.4, 95% CI 0.14,0.98), but did not seen to have effect on age of onset of the disease (chi 2 = 0.0006, p = 0.94, Odds ratio = 0.9, 95% CI 0.4,2.2). CONCLUSION: Passive smoking is associated with early onset of asthma and possibly with development of severe asthma while exclusive breastfeeding is protective against development of severe asthma but does not seem to affect the age of onset of this disease.