Early-life antibiotic exposure and childhood food allergy: A systematic review

Of the 4 studies that found a significant association, in 3 studies food allergy was defined by using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes, which do not distinguish between food intolerance and food allergy.6-8 The fourth study that found a significant association defined food allergy by using a more robust definition, namely self-reported allergic reaction (using a standardized interview) plus a positive IgE test or skin prick test result.4 One of the 2 studies that did not find a significant association also used ICD-9-CM codes but included the results of IgE or skin prick tests to define food allergy.5 The other study that did not find an association used parent-reported allergic reaction (interview) plus a report of a positive blood IgE test or positive skin prick test result.3 Among the 4 studies that found an association, the extent to which protopathic bias was considered, and the adjustment models used differed, which affects the interpretation of their results. Because IgE-mediated food allergies have been associated with concomitant IgE-mediated allergic diseases,9 3 studies6-8 adjusted for other allergic diseases. The association between antibiotics and food allergies is likely to be multifactorial. Because the microbiome plays a critical role in development of the immune system, antibiotic-induced changes in the microbiome are likely to be the predominant mechanism by which antibiotic exposure influences the risk of food allergy.1 As a result of their stronger influence on the microbiome, broad-spectrum (in contrast to narrow-spectrum) antibiotics are likely to have a greater influence on the development of the immune system and allergic disease. First author, year of publication Study design/country No. of participants/age group Antibiotic exposure Outcome definition Results Relevant allergic factors included in adjusted results Linear association observed Antibiotic class specified Eggesbo et al,3 2003 Prospective cohort/ Norway 2803/ 0-2.5 y First 6 mo of life Parent-reported immediate reaction to egg plus positive IgE test result or positive OFC result∗ OR, 1.4 (95% CI, 0.6-3.3); aOR, 1.5 (95% CI, 0.6-3.7) None No No Risnes et al,4 2011 Prospective cohort/ United States 1401/ 0-6 y First 6 mo of life Parent-reported allergic reaction (interview) plus report of a positive blood IgE test or positive SPT result OR, 1.93 (95% CI, 1.38-2.71); aOR, 1.59 (95% CI, 1.10-2.28) LRI, parental