A new study conducted by Boston researchers reports that the link between asthma and early childhood use of acetaminophen or ibuprofen may be driven by underlying respiratory infections that prompt the use of these analgesics, rather than the drugs themselves.
Analgesics like ibuprofen and acetaminophen are routinely given to treat fever in infants, and several studies have shown a link between the use of analgesics during infancy and the subsequent development of asthma and asthma symptoms including wheeze. However, although respiratory infections are a common cause of fever in infants, these earlier studies did not consider whether the underlying respiratory infection played a role in the eventual development of asthma and asthma symptoms in these children.
“Many children are given over-the-counter analgesics to treat the fever that accompanies respiratory infections, so it seemed unclear to us whether asthma and wheeze were really linked to the use of these drugs or perhaps to the respiratory infection itself,” explained study lead author Joanne Sordillo, ScD., instructor of medicine at Brigham and Women’s Hospital in Boston.
“In our study, we wanted to try to determine if accounting for early life respiratory infections mitigated the relationship between analgesic use and development of wheeze and asthma in children,” she said.
The researchers used data from 1,139 mother-child pairs who participated in Project Viva, a research study of pregnant women and their children that examined lifestyle factors during pregnancy and after birth and evaluated their effects on the development of asthma and other childhood conditions. Mothers completed questionnaires during early pregnancy, at mid-pregnancy and at one year following birth to determine acetaminophen and ibuprofen use. Also, during the first three years of each child’s life, every mother provided an annual report of any doctor’s diagnosis of asthma or wheezing symptoms.
A review of the study data found a higher exposure to acetaminophen both prenatally and during the first 12 months of life compared to ibuprofen: 70 percent of mothers reported acetaminophen use during pregnancy while only 16 percent of mothers said they had used ibuprofen while pregnant; 95 percent of children were given at least one dose of acetaminophen during infancy versus 70 percent of children who had been given at least one dose of ibuprofen. About 43 percent of children were given more than 10 doses of acetaminophen before they were a year old compared to 25 percent of children who received more than 10 doses of ibuprofen.
Next, the researchers looked at drug use and the occurrence of asthma and asthma-like symptoms overall, and then adjusted the analysis to account for respiratory infections the children experienced by the age of three. These infections included bronchiolitis, pneumonia, bronchitis, croup or any other respiratory infection.
At the conclusion of their study, the researchers found that while use of the drugs was associated with wheeze and asthma in unadjusted models, after adjusting the results to account for respiratory infections, the association between medication use in early childhood and asthma symptoms was substantially reduced.
“These results suggest that respiratory infections in infancy, and not analgesic use, are the actual underlying risk factor for asthma and wheeze in children,” said Sordillo.