However, while calling the results reassuring in an accompanying editorial, Drs. Mary Ellen Wohl and Joseph Majzoub of Children's Hospital in Boston expressed concern that the inhaled steroids, including budesonide, may stunt the growth of the lungs and other organs.
Until those questions are answered "it may be prudent to avoid the use of inhaled corticosteroids in young children with very mild asthma," they said.
Others were less cautious. Dr. Claude Lenfant, director of the National Heart, Lung, and Blood Institute, said the larger of the two studies confirms the steroids' "effectiveness while providing reassuring evidence about their safety."
"We hope these results will convince more physicians, and parents as well, that treating children with persistent asthma with inhaled corticosteroids will result in better asthma control and improved quality of life," Lenfant said in a statement.
Nearly 5 million children in the United States have asthma. Most develop symptoms by age 5 and about 35 percent of them experience symptoms at least twice a week.
In the smaller study, Drs. Lone Agertoft and Soren Pedersen of the University of Odense tracked the height of 142 fully grown children who had regularly received budesonide for their asthma. They compared their growth to the growth rates of their brothers and sisters, as well as 18 other children with asthma never treated with inhaled steroids.
"We measured the growth of these children, more than 100 children, for 10 years, and we found they grew as they should," Pedersen told the CBS News Early Show. "They reach the same height as their parents, and some were even taller."
But their study also confirmed the results of earlier research showing that growth slows down during the first year of budesonide treatment. But the reduction in growth didn't persist into adulthood, they said.
"My son was in the study, and he's been receiving this treatment for more than 12 years now," Pedersen said. "He`s taller than I am, and I'm pretty tall myself."
In the larger study, which did not follow the children through puberty, Stanley Szefler of the National Jewish Medical and Research Center in Denver and his colleagues followed 1,041 children who regularly received budesonide, another inhaled drug called nedocromil, or a placebo.
Szefler has served as a consultant to budesonide's maker as well as other companies that make asthma medications.
After more than four years of treatment, the researchers found the budesonide recipients required half as many hospitalizations and fewer trips to the doctor to treat an exacerbation of asthma, compared to children who were inhaling a placebo. They were also less likey to need the drug albuterol for asthma symptoms.
Nedocromil, sold under the brand name Tilade and made by a subsidiary of the Franco-German drug giant Aventis SA, showed better effects in the study than the placebo but was less effective than budesonide, sold as Pulmicort by the Anglo-Swedish drug company AstraZeneca.
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