Early antibiotic use linked to asthma, not atopy

Research from the UK has found a “robust and dose-dependent” association between antibiotic use in the first 2 years of life and subsequent asthma at the age of 7 and a half years.

But the data, from the Avon Longitudinal Study of Parents and Children, indicate that this is not mediated through an association with atopy, which had no significant relationship with previous antibiotic use.

Researchers, led by John Henderson at the University of Bristol, studied 5780 children who were followed up from birth. Overall, 69.1%, 46.8%, and 54.0% were not given antibiotics between the age of 0 to 6 months, 6 to 15 months, and 15 to 24 months, respectively. And, at age 7.5 years, 10.7% had asthma, 17.2% had eczema, and 8.7% had hay fever.

Children who had taken antibiotics by the age of 24 months were 75% more likely to have asthma at 7.5 years than children who had not. And, the team found that this likelihood was related to the number of courses received. For example, those who had received one course of antibiotics had a nonsignificant 11% increased odds for asthma, whereas those who had received two courses had a significant 50% increased odds, while for those who had received four or more courses, the odds were increased a significant 182%.

Additionally, children who received antibiotics during more than one of the three time periods were more likely to develop asthma by age 7.5 years than those who had only received antibiotics in one time period. In particular, children who received antibiotics in all three time periods had a 2.60-fold increased odds for asthma compared with children who did not receive antibiotics before 24 months.

However, the researchers found some evidence of reverse causation, as all the above relationships were substantially attenuated after exclusion of children who reported wheeze before the age of 18 months as well as before the age of 30 months.

“Therefore, inappropriate treatment for young children for symptoms of wheezing with antibiotics could result in a spurious association between antibiotics and later asthma,” they comment in Pediatric Allergy and Immunology.

The team also reports weaker but significant relationships between early antibiotic exposure with hay fever and eczema. However, as they found no significant relationship between antibiotic use and atopy on skin prick testing at age 7.5 years, they note the findings contradict the prevailing theory that early antibiotic exposure steers the developing immune system toward an atopic phenotype.

They therefore conclude that confirming their findings will require “a focus on non-atopic asthma in childhood in a longitudinal study with validated antibiotic prescription data and documentation of indications for antibiotic use in infants.”

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