HYATTSVILLE, Md., Dec. 28 (UPI) -- Although the rate of asthma among children has been steadily increasing for several years, it has plateaued and started to decrease in the in the last two years, according to a new study.
The 20-year trend of increases in asthma diagnosis appears to stabilized among most children, though not for the poor and children between the ages of 10 and 17, researchers at the National Center for Health Statistics report in the study, published in the journal Pediatrics.
While researchers said they're not entirely sure why overall rates have leveled, they're also not entirely sure why rates among impoverished children have not leveled off -- though they note many of the environmental factors that can influence asthma development may not be fading for poor children the way they are for others.
Since childhood asthma rates doubled between 1980 and 1995, the researchers also noted that rates were bound to stabilize or start rolling back at some point, even as increases have been slowing since 2001.
"Trends in childhood asthma have recently stopped increasing," said Dr. Lara Akinbami, of the National Center for Health Statistics, told HealthDay. "This is mainly due to the leveling off of prevalence among black children, who previously had large increases in the prevalence of asthma. However, more years of data are needed to clarify if asthma prevalence among children will continue to decline, or if it will plateau around current levels."
Researchers at the NCHS, part of the Centers for Disease Control and Prevention, analyzed data collected between 2001 and 2013 as part of the National Health Interview Survey. Overall, they report, childhood asthma prevalence increased between 2001 and 2009, before plateauing for four years and starting to drop in 2013.
Among non-Hispanic white and Puerto Rican children, and children overall in the northeast and west regions of the country, there was no change in prevalence. Rates increased, however, among children ages 10 to 17, poor children, and children in the South.
Rates of 5- to 9-year-olds, near-poor, and non-Hispanic black children, however, increased and then plateaued during the study period, while 0- to 4-year-olds, non-poor, Mexican and Midwestern children saw rates increase and then decrease. The researchers also note in the study that Puerto Rican children have the highest rate of prevalence.
The researchers said poorer children are exposed to environmental factors such as tobacco, mold, mildew, dust, cockroaches and smog more often than less poor and non-poor children. Additionally, the stress of poverty may have an effect on asthma risk, researchers said.