Conference Coverage

Early antibiotics may up food allergy risk



Antibiotic exposure during the first year of life is associated with an increased risk of food allergy in young children, according to findings from a large case-control study.

The risk is greatest among those exposed to multiple antibiotic courses, Bryan L. Love, Pharm.D., reported during a late-breaking abstract session at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.

Bryan Love

The mean number of antibiotic courses received by 1,105 case patients with food allergy was 2.65, compared with 1.84 for 6,433 food allergy–free control patients. The mean time to first antibiotic course was 181.5 days for those with food allergies, compared with 190.1 days for controls. These differences were statistically significant, said Dr. Love of the South Carolina College of Pharmacy, Columbia.

Additionally, only 24% of case patients, compared with a third of controls, had never received an antibiotic.

Later vs. earlier antibiotic exposure (during months 7-12 vs. months 0-6) also was associated with greater likelihood of developing food allergy (odds ratio, 1.98).

"This makes sense, because [months 7-12] is typically when new foods are being introduced to children," Dr. Love said.

Furthermore, the risk increased in tandem with the number of antibiotic exposures. No significant increase in food allergy risk was seen with one or two antibiotic courses, but the odds ratio became significant with three or four courses, and was highest with five or more courses (odds ratio, 2.15), he noted.

Case patients in this study were children born between 2007 and 2009 with a diagnosis of food allergy made before Dec. 31, 2010 (and after first antibiotic exposure), based on South Carolina Medicaid billing data. Certain patients, such as those with asthma, atopic dermatitis, or eczema, were excluded, because they have an increased risk of food allergy and antibiotic exposure. Controls were matched to the case patients by birth year, sex, and race.

Penicillins were the most frequently prescribed type of antibiotic, followed by cephalosporins, Dr. Love said.

The findings support the hypothesis of this study, which is that alteration of normal gut flora that occurs after antibiotic exposure might contribute to the increasing prevalence of childhood food allergy. Normal gut immune response, including the interaction with a diverse microbiome, promotes the development of food tolerance, he explained.

Though limited by the study’s retrospective design and the reliance on ICD-9 coding for diagnoses, the findings do, indeed, suggest that early antibiotic exposures are problematic. The possibility that antibiotic exposures have a causative effect with respect to food allergy development in children deserves further study, particularly given the significant use of antibiotics in young children, who receive an average of 2.2 antibiotic prescriptions in the first year of life, and the increasing incidence of food allergy, he said.

Further analysis of the data will assess whether certain antibiotic drug classes confer greater risk of food allergy, he noted.

This study was funded by the Health Resources and Services Administration. Dr. Love reported having no other disclosures.

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