Antibiotic use in infancy and symptoms of asthma, rhinoconjunctivitis, and eczema in children 6 and 7 years old: International Study of Asthma and Allergies in Childhood Phase III

Background: Phase III of the International Study of Asthma and Allergies in Childhood measured the global prevalence of symptoms of asthma, rhinoconjunctivitis, and eczema in children. Objective: To investigate the associations between the use of antibiotics in the first year of life and symptoms of asthma, rhinoconjunctivitis, and eczema in children 6 and 7 years old. Methods: Parents or guardians of children 6 and 7 years old completed written questionnaires on current symptoms and possible risk factors. Prevalence odds ratios (ORs) were estimated by using logistic regression. Results: A total of 193,412 children from 71 centers in 29 countries participated. Reported use of antibiotics in the first year of life was associated with an increased risk of current asthma symptoms (wheezing in the previous 12 months) with an OR (adjusted for sex, region of the world, language, and per capita gross national income) of 1.96 (95% CI, 1.85-2.07); this fell to 1.70 (1.60-1.80) when adjusted for other risk factors for asthma. Similar associations were observed for severe asthma symptoms (OR, 1.82; 95% CI, 1.67-1.98), and asthma ever (OR, 1.94; 95% CI, 1.83-2.06). Use of antibiotics in the first year of life was also associated, but less strongly, with increased risks of current symptoms of rhinoconjunctivitis (OR, 1.56; 95% CI, 1.46-1.66) and eczema (OR, 1.58; 95% CI, 1.33-1.51). Conclusion: There is an association between antibiotic use in the first year of life and current symptoms of asthma, rhinoconjunctivitis, and eczema in children 6 and 7 years old. Further research is required to determine whether the observed associations are causal or are a result of confounding by indication or reverse causation. (J Allergy Clin Immunol 2009;124:982-9.)