There's finally some good news about childhood asthma in the United States: After rising for decades, the number of children with the breathing disorder has finally stopped increasing and may have started falling, according to a government analysis.
"That was a big surprise," says Lara Akinbami of the National Center for Health Statistics. "We were expecting the increase to kind of continue. But in fact we saw the opposite."
The percentage of U.S. children with asthma doubled in the 1980s and 1990s and had been increasing steadily since then. The reason for the increase has remained mysterious, but there may be many possible factors, including exposure to secondhand smoke, obesity and children's immune systems failing to develop properly.
Akinbami and her colleagues detected the first change in that trend when they analyzed data from the National Health Interview Survey between 2001 and 2013.
Among children ages 17 and younger, the prevalence of asthma peaked at 9.7 percent in 2011 and then plateaued until 2013, when it declined to 8.3 percent, the researchers report Monday in the journal Pediatrics.
But asthma prevalence continues to rise among children in the poorest families and remains far more common among African-American children than white children. More than 14 percent of black children have asthma, compared with about 8 percent of white children. Black children are also much more likely than white children to suffer severe complications.
And it's not clear "whether 2013 represents just one of the fluctuations in that leveling or whether that's going to show us the beginning of a decreasing trend," Akinbami says.
The reason for the shift remains as mysterious as the rise. One possibility is that the proportion of children who are genetically susceptible to asthma may have peaked, Akinbami says.
Regardless of the cause, other experts are welcoming the trend.
"It is good news for kids," says Stephen Teach, chairman of pediatrics at the Children's National Health System in Washington, D.C. In addition to deaths and hospitalizations, asthma attacks cause children to miss school and their parents to miss work.
"It's an economic and health care drag on our system and our potential for children to develop," Teach says.
Teach and others say we still have a long way to go.
"Roughly 1 in 9 children have asthma. That's a pretty profound burden of a health condition in a population that really should be very, very healthy overall," says Elizabeth Matsui, a professor of pediatrics at the Johns Hopkins Children's Center in Baltimore. "So there's still a lot of work to be done."
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