By Doreen Samelson, Ed.D., MSCP, and Lindsey Sneed, Ph.D., BCBA-D

A 2024 study of autism screening included an important finding: Pediatric clinicians who use a standardized screening tool are more likely to flag toddlers as potentially autistic. However, the response of many families was surprising. Any family of a child flagged by the screening received an invitation to a free follow-up diagnostic evaluation—a more in-depth process to determine if the child actually was autistic. Unexpectedly, a large percentage of families didn’t attend this evaluation. Why? It’s a question worth exploring.

Getting autism screening right is important. There is broad agreement that early intervention leads to improved outcomes for children. The American Academy of Pediatrics recommends routine screening for toddlers at 18 and 24 months. Unfortunately, as the study authors write, there is “inconsistent adherence to screening guidelines in community practice.” That’s a polite way of saying that the quality of autism screening varies widely—and sometimes isn’t very good.

The First Randomized Controlled Trial to Evaluate Autism Screening of Toddlers

The authors of the study, researchers at Drexel University’s A.J. Drexel Autism Institute, set out to compare outcomes between children in two groups. In the experimental group, pediatric practices received training in the use of a standard autism screening tool, M-CHAT-R/F. In the usual care group, clinicians screened children for autism using their own discretion, with or without a screening tool like M-CHAT-R/F. The study, published in the Journal of the American Academy of Child & Adolescent Psychiatry, is believed to be the first randomized controlled trial to evaluate screening toddlers for autism.

The differences between the two groups were striking:

• In the usual care group, clinicians flagged 1.49 percent of children for possible autism.
• In the experimental group, clinicians flagged 7.38 percent of children—a rate nearly five times higher than in the other group.

Significantly, clinicians in the experimental group flagged children three months earlier than those in usual care. These children were more likely to have a milder clinical presentation, with higher measures of social skills and language skills. These last two points are important, given the benefits of early intervention for autism and the inherent challenges of identifying individuals with milder autism, but not particularly surprising.

Some Parents Declined a Diagnostic Evaluation

In the usual care group, among the families whose children were flagged, 92 percent chose to attend a no-cost diagnostic evaluation of their child. In contrast, the response rate of families in the experimental group was unexpected: Only 53 percent chose to attend the evaluation. Nearly half did not.

This result stood out to the study authors. They write, “It is possible that clinicians in usual care practices expressed more urgency to families about having their child attend the diagnostic evaluation, perhaps because of increased confidence in their clinical judgment about children’s likelihood of autism (as opposed to ‘trusting the screening results’).”

The authors also mention the possibility that “child characteristics contributed to the lower proportion of families electing to receive the diagnostic evaluation despite screening positive.” This seems like a strong possibility. Parents of children with milder symptoms (who were more frequently flagged in the experimental group) may have felt less urgency about attending their diagnostic evaluation. As well, the timing of the study, which overlapped with the COVID-19 epidemic, may have left some parents feeling they were better off staying at home.

Still, the fact that half of the parents in the experimental group did not attend a free evaluation of their child highlights a significant gap in understanding. Clinicians and parents of children with milder autism symptoms might not recognize the potential importance of an early diagnosis or feel the urgency to act. This suggests a need for educational initiatives targeted to both groups.

Parents must be empowered with accessible, practical information about the ways early intervention can dramatically improve outcomes, even for children with mild symptoms. Clinicians, in turn, need tools and training to effectively communicate the value of follow-up evaluations and address families’ potential concerns.

Looking Ahead to the CDC’s Report on Autism Prevalence Rates

The study illuminates some of the issues that make autism difficult to screen for and diagnose. These issues may be especially relevant in a few weeks, when the CDC would typically publish a major report on autism prevalence rates. Every two years, the report offers the most comprehensive view of the state of autism among children in the United States. That said, this is not a typical year, and the new administration may have other plans in mind.

Lindsey Sneed, Ph.D., BCBA-D, is vice president of clinical excellence at the nonprofit Catalight, which provides access to innovative, individualized care and clinical research. She is also an adjunct faculty member at the University of San Francisco. She conducts applied research evaluating the efficacy of different models of care for children with developmental disabilities and contributes to the development of new care models.