The epidemic increase in asthma incidence among children in the U.S. and other industrialized countries may finally be stabilizing.
But allergy and asthma is on the rise in many developing countries that have not seen similar increases in the past, according to a global study that included more than half a million children living in 56 countries.
A researcher for the International Study of Asthma and Allergies in Children (ISAAC) tells WebMD that the biggest increases are being seen in heavily populated regions that are becoming more industrialized, such as India and Asia Pacific.
"The rise may be due to a composite of things that we associate with a Western lifestyle, such as the way we eat, the way we build and live in our homes, and our exposure to chemicals," says University of Auckland pediatrics professor Innes Asher.
Overall, the global incidence of childhood allergies, asthma, and eczema increased by 0.5% annually between the mid-1990s and 2003, according to the ISAAC data.
While that might not sound like a lot, the fact that the largest increases occurred in some of the most heavily populated countries is cause for concern, Asher and colleagues noted.
"Urban centers in developing countries might have few resources to implement management programs for these diseases in the face of overwhelming infectious diseases," they wrote.
Increases in the prevalence of allergies, asthma, and eczema were more commonly seen among children between the ages of 6 and 7 than among children aged 13 and 14.
Asthma incidence among the older children in the U.S. and the U.K. remained relatively stable between the mid-1990s and 2003.
Asthma Deaths Dropping
The study is not the first indication that we may have seen the worst of the epidemic increases in childhood asthma in the U.S., says American Lung Association (ALA) chief medical officer Norman Edelman.
Roughly 20 million Americans have asthma -- three times as many as 25 years ago. One in eight children suffers from the disease, according to figures from the ALA and the CDC.
Edelman tells WebMD that childhood asthma cases in the U.S. began leveling off four or five years ago. Asthma deaths have also dropped during the period, from around 5,000 to 4,000 a year.
Edelman is a professor of medicine at Stony Brook University, New York.
"We can't quite call this a trend, because statistics tend to go up and down, but it is certainly encouraging," he says. "We are not seeing big declines in asthma, and we are not back to where we were 20 years ago. Not even close."
SOURCES: Asher, M.I. The Lancet, Aug. 26, 2006; vol 368: pp 733-743. Innes Asher, professor of pediatrics, University of Auckland, New Zealand. Norman Edelman, MD, chief medical officer, American Lung Association; professor, Stony Brook University, Stony Brook, N.Y.
By Salynn Boyles
Reviewed by Brunilda Nazario