Secondhand, or passive, exposure to tobacco smoke led to an additional mean loss of 5% predicted lung function in young cystic fibrosis (CF) patients than in those who were unexposed, a review study shows.
Researchers analyzed the results of six studies, which used a clinical test known as percent predicted forced expiratory volume in one second (FEV1%) to measure lung function in pediatric patients.
The “findings may be useful to inform future environmental health research agendas and reduce disparities in pediatric CF care,” the researchers wrote in “Lung function and secondhand smoke exposure among children with cystic fibrosis: A Bayesian meta-analysis,” which was published in the Journal of Cystic Fibrosis.
CF is a genetic disease that can trigger many symptoms, including severe lung infections. It’s marked by the production of thick, sticky mucus, which builds up in the lungs and other organs.
Several tools can help diagnose and monitor CF. Lung function tests such as FEV1%, which corresponds to the maximum amount of air a patient can forcibly expel during the first second after a deep inhalation, are among them.
Passive tobacco smoke exposure — a combination of the smoke resulting from a burning tobacco product and which a smoker exhaled — “has been linked to a decrease in FEV1% predicted” for young patients with CF, the researchers wrote, noting, however, that “little has been done to coalesce estimates of the association between secondhand smoke exposure and lung function decline,” even though the studies are available.
Secondhand smoke and lung function in young people
This led a team led by researchers in the U.S. to evaluate the association between young patients exposure to tobacco smoke and alterations in their lung function as measured by FEV1%
They analyzed six studies from 1992 to 2022 that included patients who weren’t yet adults. All the studies used FEV1% as an outcome measure to test lung capacity.
There was a significant drop in lung function in patients passively exposed to tobacco smoke, results showed. The affected patients had a mean lung function that was 5.11% predicted lower (FEV1% measured) than those who were unexposed.
The researchers reported a moderate to large diversity between the studies in the analysis. Despite these differences, the effects were the same — passive smoke exposure is associated with worsened lung function and suggest its consequences to young CF patients is “clinically meaningful and heterogeneous.”
The data “corroborate the assertion that secondhand smoke exposure negatively affects pulmonary function,” the researchers said, adding the studies represent a large percentage of the U.S. population of pediatric patients with CF, even though only a few were analyzed. Thus, the results may have implications for supporting research agendas for environmental health interventions in pediatric CF care, they said.