Childhood asthma rates appear to have stopped rising among many US groups, but not among the poorest kids or children aged 10 and older, a study suggests.
Overall, asthma prevalence among kids under 18 had been rising for decades, until it peaked at 9.7% in 2009. Then it held steady until 2013, when it dropped to 8.3 percent from 9.3 percent the previous year, researchers reported online December 28 in the journal Pediatrics.
"International data on asthma prevalence over time shows that trends appear to be levelling off in many countries, and suggests that the trend in the United States seems to be following a general pattern," said lead study author Dr. Lara Akinbami of the U.S Center for Disease Control and Prevention's National Center for Health Statistics in Hyattsville, Maryland.
Even though the recent decline is statistically meaningful, it's too soon to tell whether the decrease from 2012 to 2013 might be the start of another plateau or the beginning of a meaningful decline in asthma cases, Akinbami said by email.
In addition to the scant number of years to assess a shift in asthma trends toward the end of the study period, it's also possible that changes in the way U.S. researchers collected survey data on childhood asthma might have influenced the results.
"It also doesn't clearly identify which factors underlie changes in trends," Akinbami added. "There is likely a complex story on why asthma prevalence has apparently stopped increasing."
Part of the complexity stems from variations in rates of asthma based on age, income, region or race and ethnicity, the study found.