Children with highest levels of FeNO more likely to develop asthma: Study

Children with elevated levels of exhaled nitric oxide (FeNO) are at increased risk for developing asthma, particularly among children without a parental history of the disease, a study by US researchers at the Keck School of Medicine of the University of Southern California (USC) has found. The study is published ahead of print in the European Respiratory Journal.

The findings suggest that FeNO may be a useful biomarker for identifying children at risk for the disease, and in developing strategies for preventing asthma. Researchers found that children with the highest levels of FeNO were more than twice as likely to develop asthma compared to those with the lowest levels. Higher levels of FeNO were linked with development of asthma most often in children whose parents had no history of the disease.

Nitric oxide is a gas that is produced by the cells that line the inner wall of the lungs' airways, and may be a marker of the inflammatory process that occurs in the lungs prior to asthma onset. Although a number of studies have documented the growing prevalence of asthma during the past several decades, the factors causing the rapid rise of the disease are not fully understood.

"We believe this is the first study to demonstrate the predictive value of FeNO for identifying children who are at risk for developing asthma," said Tracy Bastain, M.P.H., a doctoral student in the Department of Preventive Medicine at the Keck School of Medicine and the lead author of the study. "Our results were strongest in children whose parents had never had asthma, suggesting that FeNO might help to identify additional susceptible children."

The USC study drew upon data from the Children's Health Study (CHS), the longest epidemiologic investigation ever conducted on environmental contribution to children's respiratory health. In 2004, USC researchers measured the level of FeNO in 2,206 healthy, asthma-free children from 13 communities in Southern California. Between 2004 and 2007, they tracked the respiratory health of the children with annual follow-up questionnaires.

Previous studies have found that FeNO is elevated in children with current asthma or allergies. However, researchers at USC were able to draw upon a large cohort of healthy children to identify FeNO as a potential biomarker for asthma development, Bastain said. Further studies are needed to establish whether FeNO can be used in the clinical setting to assess a child's individual risk for developing asthma.

"Asthma is a very important clinical and public health problem, and there is still much to be learned about the causes of asthma before the burden of asthma can be reduced," said Frank Gilliland, M.D., Ph.D., professor of preventive medicine at the Keck School of Medicine, director of the Southern California Environmental Health Sciences Center and senior author of the study. "Showing a link between FeNO and later asthma development provides new clues to the development of asthma."