On Autism, Shifting US Standards Cloud the Number of Cases


Are there more cases of autism than ever?

The answer may depend on which criteria are used to diagnose the developmental disorder.

The latest report by the U.S. Centers for Disease Control and Prevention uses two sets. One shows a growing number of children with autism. The other, when strictly applied, identifies 18% fewer cases.

For now, the report, which was published last week, gives priority to the looser standard, but when the CDC issues its next report two years from now, the more stringent measure will take precedence.

The current report tracked the estimated prevalence of autism in more than 300,000 children who were 8 years old in 2014. Statistically, the children, who reside in 11 communities in as many states, aren’t nationally representative, but the findings inform treatment and policy decisions across the country.

The conclusions are based primarily on criteria drafted in 1994 for the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders. Using those standards, 1 in 59 children had autism, compared with 1 in 68 just two years earlier.

For the sake of comparison, the report assessed 263,775 children using both the old and new standards, which were drafted in 2013.

Based on the old standards, 4,658 were autistic. With the new criteria, 4% fewer, or 4,498, were—but that number includes 681 on the basis of a previous diagnosis. Without them, only 3,817 children would have been diagnosed, or 18% fewer than the number identified with the old rules.

It’s possible some of those kids would meet the new criteria, but the documented record of their symptoms didn’t support that conclusion.

“We can’t know if a child definitely didn’t meet the criteria,” said Daisy Christensen, the surveillance team lead for the developmental disability branch of the CDC. “We’re reliant on what is documented in the record.”

At this stage, the Autism Society, a nonprofit advocacy group founded in 1965, isn’t concerned about the change in the criteria in part because it’s too soon to see how it may alter diagnoses.

“If in the past they were called autistic and now they are not labeled anything, how will they get help?” said

Scott Badesch,

the society’s chief executive. “If they’re labeled something else and can get help for their symptoms, that’s great.”

This isn’t the first time autism has been affected by changing definitions.

In the U.S., it wasn’t a unique category in the diagnostic manual until 1980. The definition changed in 1987 and again in 1994, when it was broadened to include a range of behaviors that varied in characteristics and severity—and not all of the behaviors were required for a diagnosis.

Now, Autism Spectrum Disorder is a single category encompassing previously distinct diagnoses including autistic disorder, Asperger’s syndrome and pervasive developmental disorder-not otherwise specified, or PDD-NOS, a diagnosis applied to individuals who didn’t fully meet the criteria for the other subtypes. In addition, only individuals with both social communication and interaction disorders as well as restricted or repetitive behaviors will be diagnosed as having autism.

“One of the goals of the revision was to tighten what was criticized as unclear and too lenient criteria for PDD-NOS,” said Catherine Rice, director of the Autism Center at the Emory University School of Medicine.

Given that, a reduction in diagnoses isn’t surprising. The CDC report isn’t sufficient to determine to what degree this might happen moving forward, but a number of studies have tried to examine how closely the different criteria align.

Most conclude that a substantial number of individuals previously diagnosed with autism would not meet the new requirements—although the CDC is careful to point out that no one will be stripped of the diagnosis.

“You’re grandfathered in,” said Stuart Shapira, chief medical officer and associate director for science for the CDC’s National Center on Birth Defects and Developmental Disabilities.

Among the recent studies comparing the different standards is an analysis published last year in Journal of Autism and Developmental Disorders.

That study, of 439 children and adolescents who received a diagnostic evaluation at one of six centers affiliated with the Autism Treatment Network, found that 20% who met the old criteria for Asperger’s syndrome and 75% who met the criteria for PDD-NOS did not meet the new criteria.

The study differed from other analyses that applied the new standards to previously collected data. A problem with that approach is that it’s impossible to know how the documentation might have differed if the clinicians who evaluated the individuals had adhered to the new standards.

When the CDC completes its next autism study, the new diagnostic criteria will take precedence, but the previous standards will also be applied to a subset of cases to see how the two measure up.

Write to Jo Craven McGinty at Jo.McGinty@wsj.com



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