Background: It has been hypothesized that antibiotic use early in life may increase the subsequent risk of asthma. We have conducted an ecologic analysis of the relationship between antibiotics sales and the prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and atopic eczema in 99 centres from 28 countries.
Methods: Data for antibiotics sales for 28 countries were obtained from the Institute for Medical Statistics (IMS), Health Global Services, UK and converted to defined daily doses (DDD). Data on the prevalence of symptoms of asthma, rhinitis, and eczema in 13-14 year olds were based on the responses to the written and video questionnaires from the International Study of Asthma and Allergies in Childhood (ISAAC). The analysis was adjusted for gross national product (GNP) as an estimate of the level of affluence.
Results: In general, there was a positive association between per capita antibiotics sales and the prevalence of symptoms for asthma, rhinitis, and eczema, but the associations generally became negative once the analyses had been adjusted for GNP. In particular, there were non-significant negative associations between total antibiotics sales and the prevalence of wheeze ever, wheeze in the last 12 months, nose problems with itchy-watery eyes, itchy rash in the last 12 months, and eczema ever. On the other hand there were weak non-significant positive associations for asthma ever, nose problems ever, nose problems in the last 12 months, and itchy rash ever. There was a statistically significant positive association with wheeze at rest as measured by the asthma video questionnaire; however, even this association was weak and would not account for more than a 1% difference in asthma prevalence between countries.
Conclusions: These findings are generally not consistent with the hypothesis that antibiotic use increases the risk of asthma, rhinitis, or eczema. If there is a causal association of antibiotic use with asthma risk, it does not appear to explain the international differences in asthma prevalence.
Int J Epidemiol; 2004: 33(3).