Children treated with antibiotics in their first year of life appear to have a significantly higher risk of developing asthma compared with babies not given the drugs, a Canadian study suggests.
The study, published in the June issue of the journal Chest, found that the risk for asthma doubled in tots receiving antibiotics for non-respiratory infections, as well as for youngsters who received multiple antibiotic courses and who did not live with a family dog before their first birthday.
“Antibiotics are prescribed mostly for respiratory tract infections, yet respiratory symptoms can be a sign of future asthma,” said lead author Anita Kozyrskyj of the University of Manitoba. “This may make it difficult to attribute antibiotic use to asthma development.”
“Our study reported on antibiotic use in children being treated for non-respiratory tract infections, which distinguishes the effect of the antibiotic,” Kozyrskyj said in a release.
The study, conducted by researchers at the University of Manitoba and McGill University in Montreal, is not the first to link an increased risk of asthma to early antibiotic use. Last year, a University of British Columbia analysis of seven studies involving more than 12,000 children found a similar doubling of risk.
The Manitoba-McGill researchers analyzed prescription records for more than 13,000 children from birth to age seven, zeroing in on antibiotic use prior to a child’s first birthday and the development of asthma by age seven.
Antibiotics were prescribed for various conditions, including lower respiratory tract infection (bronchitis, pneumonia), upper respiratory tract infection (otitis media, sinusitis) and non-respiratory tract infection (urinary infections, impetigo).
The study showed that six per cent of children had asthma at age seven, while 65 per cent had received at least one antibiotic prescription during the first year of life – 40 per cent for otitis media (middle-ear infection), 28 per cent for other upper respiratory tract infections, 19 per cent for lower respiratory tract infections and seven per cent for non-respiratory tract infections.
Results showed that antibiotic use in the first year was significantly associated with greater odds of asthma at age seven. The likelihood of asthma rose with the number of antibiotic prescriptions: children given more than four courses of the drugs had 1.5 times the risk of asthma compared with children who received no antibiotics at all.
When the researchers looked at reasons for antibiotic use, it appeared asthma at age seven was almost twice as likely in children receiving an antibiotic for non-respiratory tract infections compared with children who had not received the drugs.