May 4 2004
Children with asthma whose parents smoke at home are twice as likely to have asthma symptoms all year long than children of non-smokers, a new study shows.
Overall, in a nationwide sample of children with asthma, about 13 percent of parents of asthmatic children still smoke — even though second-hand smoke is known to trigger asthma attacks and symptoms in kids.
Those findings, made by University of Michigan researchers and scheduled to be presented here on May 4 at the Pediatric Academic Societies Annual Meeting, reinforce the importance of educating parents about how their own smoking can affect their children with asthma. The study is based on data from in-depth phone interviews with 896 parents of asthmatic children ages 2 to 12 years in 10 states.
Those interviews were done as part of the Physician Asthma Care Education (PACE) project, which is designed to improve asthma education for physicians, and consequently the health of their young patients who have asthma. The chronic condition affects one in every seven children.
The new analysis was conducted by Kathryn Slish, a researcher in the U-M Department of Pediatrics, with assistant professor of pediatrics Michael Cabana, M.D., M.P.H., M.A. The PACE project is led by U-M School of Public Health Dean Noreen Clark, Ph.D., and funded by the Robert Wood Johnson Foundation.
“We set out to look at children who have seasonal asthma symptoms, but found that a substantial percentage have symptoms year-round,” says Slish. “We looked more closely and found a strong relationship between parents’ smoking status and the likelihood that their child would have problems all year long.
“It’s not rocket science, since it’s well known that second-hand smoke can trigger asthma in children,” Slish continues. “But it’s astounding that so many parents smoke around their asthmatic kids, and don’t stop even though their children are having trouble breathing all year.”
The study echoes findings of previous research by the Centers for Disease Control and Prevention, which looked at whether children had had severe asthma symptoms on more or less than 300 days per year, and found a strong correlation to parent smoking among those with more than 300 days.
“We used a different approach than the CDC, and looked at 90-day blocks of time corresponding to a season,” says Cabana. “The only other factor that was associated with year-round symptoms was Medicaid insurance coverage.”
Slish and Cabana note that their findings should provide even more reason for pediatricians, family physicians and nurses to broach the subject of smoking with the parents of any child diagnosed with asthma, and to steer parents who smoke toward resources that can help them quit.
“By addressing the issue directly, and reminding parents how second-hand smoke can affect their children, perhaps we can cut down on the number of kids having symptoms throughout the year,” Cabana says.
"Even a very brief intervention with physicians encouraging patients to quit smoking has been shown to be successful," adds Clark.
Part of the PACE project is teaching physicians how to counsel asthmatic patients and their parents on avoiding asthma “triggers” — substances in the air that can bring on an asthma attack or lesser symptoms. Triggers include dust, pollen, pet dander, stress, cockroach droppings, mold, air pollution, exercise, cold air — and second-hand smoke. Some triggers, such as pollen, occur only during some times of the year, while others are present year-round and are mainly linked to indoor exposure.
The interviews conducted for the current study were part of the baseline data-gathering effort for the PACE project. Parents of young patients of participating doctors were interviewed at length about many factors. They were asked to recall the number of days during each three-month period of the last year that their child experienced daytime asthma symptoms, nighttime asthma symptoms, or limits on their daily activity due to asthma-related precautions or symptoms.
If a child had had symptoms on 27 or more days, or seven or more nights, in a 90-day season, he or she was considered to be in “peak” or persistent asthma symptoms during that time — a definition laid out by the National Heart, Lung, and Blood Institute of the National Institutes of Health.
Most of the children — 84 percent — in the study had peaks in none, one, two or three seasons of the past year. But 16 percent of the children had peaks in all four seasons — meaning they were experiencing symptoms nearly one-third of the entire year regardless of what seasonal triggers might be present.
Two-thirds of the children in the study were boys, and 12 percent were African-American. The mean age was around 7, and 61 percent used some sort of daily medication to control their asthma. More than 90 percent of the parents interviewed were mothers. Parents were asked directly if they smoked, and 13 percent answered yes.
Three-quarters of the households had private insurance, while 14 percent were insured through Medicaid. The remainder had other government insurance or paid for healthcare themselves. Just over 40 percent of the children lived in temperate climates, where differences between seasons were not dramatic.
When the researchers performed a statistical analysis to look at which factors were most associated with year-round symptoms, Medicaid status and parental smoking both were linked to a more-than-doubled likelihood.
The researchers hope to continue their evaluation of parental smoking behavior as the PACE project continues, and follow-up interviews with parents take place after their children’s doctors receive training in evidence-based asthma care and patient communication.