Prevalence Estimates for Autism Spectrum Disorder Now Exceed 1%
Pauline Anderson



Information from Industry
How can you manage your malpractice risk more effectively? The role of risk management is not to eliminate all risk but to anticipate and manage risk. October 6, 2009 — Results of a new survey show that in 2007, 673,000 children in the United States — or 1.1% of those aged 3 to 17 years — had autism spectrum disorder (ASD), up from previous prevalence estimates.

The new report shows that boys are about 4 times more likely to have ASD than girls, and the odds of having this condition are greater among white children.

The figures, based on data from the 2007 National Survey of Children's Health conducted by the Centers for Disease Control and Prevention's National Center for Health Statistics, were published online October 5 in Pediatrics.

The prevalence is higher than past estimates, possibly because of increased awareness among parents and practitioners, the broadening of criteria for ASD, and improved identification of the disorder by healthcare providers, speculated Michael D. Kogan, PhD, from the Maternal and Child Health Bureau, Health Resources and Services Administration, US Department of Health and Human Services, in Rockville, Maryland, and colleagues.

Continual monitoring of ASD remains an urgent public health priority, the authors conclude, since early intervention is associated with better outcomes for these children.

Higher Prevalence

Between April 2007 to July 2008, telephone interviews were completed for 91,642 children younger than 18 years. Analysis for this study was limited to the 78,037 children 3 to 17 years of age.

Interviewers asked parents if a healthcare provider had ever told them that their child had autism, Asperger's disorder, pervasive developmental disorder, or other autism spectrum disorder. Parents whose child had been so identified were asked if their child currently had autism or ASD and, if so, whether it was mild, moderate, or severe.

The researchers also analyzed the prevalence of co-occurring emotional, behavioral, and developmental problems among children 6 to 17 years currently with and without ASD.

They found that the prevalence of ASD was 110 per 10,000 children, markedly higher than previous estimates. According to background information in the study, prevalence estimates have risen steadily, from the 1960 to the 1980s, when estimates ranged from 2 to 5 in 10,000, to the 2000s, when estimates ranged from 30 to 60 in 10,000; in most recent reports, estimates range from 50 to 90 per 10,000.

Estimates by Age

When estimates were broken down by age, the study showed that the odds of a child having ASD were 54% greater for children 6 to 8 years of age, and 83% greater for children 9 to 11 years of age, than for children 15 to 17 years of age. It also showed that about 4 times more boys than girls are affected by ASD.

Non-Hispanic blacks and multiracial children had 57% lower odds of having ASD than non-Hispanic white children, and non-Hispanic multiracial children had 42% lower odds. These findings "indicate the need for further research on the validity of ASD diagnostic methods and the developmental trajectory according to race," the authors write.

The study also showed some geographic differences, with children in the Midwest and Northeast having marginally higher odds of having ASD than children living in the West.

Mild to Severe

ASD was described as mild in about half (49.6%) of the children, as moderate in 33.9%, and as severe in 16.5%.

ASD children whose parents had less than 12 years of education were more likely to have the condition rated as moderate or severe. These children had twice the odds as children with higher parental education of being described as not currently having ASD.

Almost 40% of children who were ever diagnosed with ASD did not currently have the condition. The authors speculate that this is because of a lack of precision in diagnosing ASD at a young age. Many of these youngsters might have had other mental health and developmental conditions or parents might have reported that their child was not currently diagnosed with ASD because they weren't receiving services, they write.

Almost all children who had ever had a diagnosis of ASD also had other disorders. About 87.3% of children with ASD and 81.6% of those ever diagnosed but not currently reported as having ASD had attention-deficit disorder or attention-deficit/hyperactivity disorder, anxiety, depression, or other disorders.

"Call to Action"

According to background information in the study, the life-time healthcare costs for a person with autism are estimated to be more than $16 million.

In a statement following the study's publication, the Autism Society said that the new data should be a "call to action" to the government to improve and increase services and supports.

"Families today are asking: How high must these prevalence rates rise before the nation responds," Lee Grossman, president and CEO of the Autism Society said in a statement. "Significant resources must be directed toward screening and diagnosis, affordable interventions that treat the whole person, and comprehensive education plans to foster lifelong skill development so that people with autism will have the ability to work and live independently."

Reflected in Practice

Asked to comment on these new findings, Phillip C. DeMio, MD, who treats some 2000 children (700 are active) with autism at his practices in Seven Hill and Worthington, Ohio, said he has also observed a significant increase in the prevalence of the disorder. "I have seen the statistics at state levels go up every year," he said.

Dr. DeMio said that most of his patients are younger than 10 years, although he also treats many teens, and agreed that he sees many more boys than girls in his office.

Dr. DeMio, who has a background in toxicology and is the father of a child with severe regressive autism, said he is convinced that ASD is not wholly a genetic disorder. He pointed out that he has several children in his practice whose twin is not affected by ASD or is much less severely affected.

The 2007 National Survey of Children's Health was funded by the Health Resources and Service Administration's Maternal and Child Health Bureau. The authors have disclosed no relevant financial relationships.

Pediatrics. 2009;124: Published online October 5, 2009.