Family history has limited predictive value for asthma risk

Although a family history of asthma is associated with increased risk of asthma in children, family history does not successfully predict enough cases of childhood asthma to be a useful tool in guiding widespread environmental prevention efforts, a new study concludes.

Directing environmental efforts like housing improvements or hot-water laundry facilities to all families with asthmatic children -- regardless of family history -- "would probably target a higher proportion of children likely to benefit from such interventions," according to Wylie Burke, M.D., Ph.D., of the University of Washington and colleagues.

However, the asthma risk associated with family history might motivate individual parents to take steps to prevent asthma complications like removing rugs and using mattress covers, say the researchers.

"Knowledge of the risk associated with a family history of asthma might also help healthcare providers and parents to identify early signs of asthma and to be more proactive about treatment," Burke and colleagues say.

Asthma affects 14 million to 15 million Americans and leads to nearly 500,000 hospital visits and more than 5,000 deaths each year. Rates of sickness and death are particularly high among low-income minority children.

"These statistics suggest that strategies identifying children at increased risk of asthma might have a public health benefit," the researchers say.

To determine if family history might be such a strategy, Burke and colleagues analyzed data from 33 previous studies of asthma and family history in populations from 20 countries. The researchers found that a family history of asthma, where first-degree relatives such as a parent or sibling had asthma, was a consistent risk factor for childhood asthma.

Yet in the 10 studies where Burke and colleagues could calculate the exact percentage of asthma cases predicted by family history, the history factor was linked to fewer than half of the asthma cases and "failed to identify the majority of children at risk," they say.

The study was published in the February issue of the American Journal of Preventive Medicine and supported by grants from the Centers for Disease Control and Prevention, Association of Schools of Public Health and the National Institute of Environmental Health Sciences.

FOR MORE INFORMATION
Health Behavior News Service: 202-387-2829 or www.hbns.org.
Interviews: Contact Dr. Wylie Burke at 206-221-5482.
American Journal of Preventive Medicine: Contact the editorial office at 619-594-7344.

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