Asthma risk increased by early use of antibiotics

Mar 15 2006

Researchers suggest that when children are exposed to antibiotics in the first year of life it may increase the risk of them developing asthma later in childhood.

They suspect too that there may be an even higher risk with each additional course of antibiotics.

They do however say they cannot exclude the possibility of "reverse causation" in which the presence of asthma leads to more frequent respiratory tract infections, which in turn increases the rate of antibiotic use.

The prevalence of asthma in western countries has increased over the last three decades, and Dr. Carlo A. Marra and colleagues at the University of British Columbia in Vancouver say in the same period there has been a greater exposure of infants to antibiotics.

Marra says epidemiological evidence linking antibiotic use with asthma risk is conflicting and in order to review existing evidence, the team identified seven studies that specifically examined the relationship between being given at least one prescription for an antibiotic in the first year of life and the development of physician-diagnosed asthma between the ages of 1 and 18 years.

The studies apparently included 12,082 children and 1817 asthma cases and the data showed that the likelihood of developing asthma was doubled among children with antibiotic exposure before 1 year of age.

Marra's team also combined data from five studies analyzing a potential dose-response relationship, which included 27,167 children and 3,392 asthma cases and found the chances of having asthma increased 16 percent with every additional course of antibiotics given during the first year of life.

The researchers suggest that further research is needed to address concerns such as reverse causation and the types of antibiotics used to definitively answer whether or not antibiotic use early in life is associated with later asthma risk.

Marra does say that although antibiotics are commonly used to treat upper respiratory tract infections and bronchitis, most of these infections are viral and antibiotics are ineffective in such cases.

The research is published in the current edition of Chest.