More than 2.2 percent of children age 3 to 17 now have autism, a near 80 percent increase in prevalence from 2011-2013, according to new survey released Friday. Researchers noted that the rise is likely due to a change in the format of the questionnaire, reported The Washington Post.
The report from the Centers for Disease Control and Prevention and National Center for Health Statistics estimates that about one in 45 children aged 3 and older have autism, compared to the last estimate of one in 68 kids.
"One in 45 is what we think is the most accurate parental report of autism to date. I think within this report we found that the way that we ask the parents about autism spectrum disorder can have an impact on the way the parents respond to the question," said Benjamin Zablotsky, an epidemiologist at the National Center for Health Statistics who helped lead the study, reported CNBC.
"We feel we are asking the question in a better way than before," he added, noting it's probably the most accurate estimate yet.
Researchers stressed that the study, which looked at data collected in 2014, doesn't necessarily indicate a huge increase in autism occurring among children. They say it's important to take into account a change in the order of questions compared to previous years.
In previous years, many parents of children diagnosed with autism spectrum disorder reported it as a developmental disability rather than as autism, since the developmental category was listed first. So the new survey flipped the two categories, which researchers believe provides a more accurate estimation, according to the Post.
The layout change also led to a decrease in the number of people reporting "other developmental delays" in their children, declining from 4.84 percent based on 2011-2013 data to 3.57 percent in 2014. However, the overall number of parents who reported any developmental disability in their child remained steady at about 5.75 percent, according to USA Today.
Other studies have also found rising rates of autism over the past two decades, but scientists still have trouble explaining why.
Katherine Walton, an assistant professor of psychiatry and psychology at Ohio State University, who wasn't involved in the study, said that it's possible that more children actually are developing the condition, but also noted that the definition of autism is much broader than it was decades ago, according to USA Today. Parents are also more educated on autism, resulting in an increase in testing of younger children.
Diagnosing autism can be a difficult task, since there is no blood test or simple swab. Instead, a doctor must study a child's behavior and development over time. An October study from the Center for Health Statistics found that 13 percent of children who were determined to have autism later had their diagnosis reversed after further testing, reports CNN.
