First large-scale study of universal screening for autism raises questions about accuracy

Summary: Study urges doctors to continue screening all toddlers for ASD, but recommends changing to M-CHAT screening methods to improve accuracy and address current disparities.

Source: CHOP

In the first large, real-world study of universal screening for autism spectrum disorder (ASD) in toddlers, researchers at Children’s Hospital of Philadelphia (CHOP) have found that the most widely used and researched screening tool is less accurate than shown in previous studies conducted in research laboratory settings. The new study also revealed significant disparities in detecting early autism symptoms in minority, urban and low-income children. The findings were published online today in the journal Pediatrics.

The American Academy of Pediatrics (AAP) recommends screening all toddlers for ASD at their 18- and 24-month primary care check-ups using the Modified Checklist for Autism in Toddlers with Follow-Up (M-CHAT/F), a two-stage parent survey to determine whether a child may have autism, with the follow-up designed to eliminate false positives. However, most studies to evaluate the accuracy of the M-CHAT/F have been conducted in research settings rather than in real-world clinical settings. Therefore, very little was known about screening in the recommended primary care setting, nor about longer-term outcomes for children who screened negative on the M-CHAT/F. The CHOP study is the first to look at outcomes of truly universal screening in a real-world primary care setting.

“As part of a large pediatric network implementing universal screening, we found ourselves in a unique position to find answers to critical questions about the accuracy of the M-CHAT, and to determine how many children are missed by early, universal screening,” said lead author Whitney Guthrie, PhD, a clinical psychologist specializing in early diagnosis at CHOP’s Center for Autism Research. “Early intervention has been shown to improve outcomes, potentially into adulthood. We know that early and accurate screening and diagnosis is the crucial first step in helping children access those effective, autism-specific therapies.”

The CHOP research team studied the electronic health records (EHR) of 25,999 patients screened in primary care using the M-CHAT/F between the ages of 16 and 26 months, and systematically followed these children until 4 through 8 years of age using the EHR. Ninety-one percent of these children were screened using the M-CHAT/F, meaning that nearly universal screening of all children in primary care was achieved.

The study showed that the M-CHAT/F detected only about 40% of children who went on to be diagnosed with ASD. However, children who screened positive were diagnosed seven months earlier than those who screened negative, suggesting that early screening may facilitate early intervention. Overall, 2.2% of children in the study were ultimately diagnosed with ASD, which is consistent with the Centers for Disease Control and Prevention (CDC) estimates nationally.

This shows a young girl sitting against a wall
The study showed that the M-CHAT/F detected only about 40% of children who went on to be diagnosed with ASD The image is in the public domain.

“Although our findings reveal significant shortcomings in current screening tools, we want to be clear that we are not recommending that pediatricians stop universal screening,” said Guthrie. “Instead, clinicians should continue to screen using the M-CHAT/F, while being aware that this screening tool does miss some children with ASD. Any clinical or parental concerns should be taken seriously, and warrant continued surveillance even if a child screens negative on the M-CHAT/F. And of course, a screen positive on the M-CHAT/F warrants referral so that children with ASD can be diagnosed and receive early intervention.

“Pediatricians should also be aware of disparities in screening practices and results in children of color and from low-income backgrounds.”

The CHOP study found that the 9% of children who did not receive screening at 18 or 24 months were disproportionately from racial minority groups; from non-English speaking households; and from households with lower median income and who receive Medicaid. When screening was administered, these same children were more likely to receive a false positive result. The M-CHAT was also less accurate in girls than in boys.

“Persistent racial and economic disparities in autism screening and diagnosis are a cause for great concern, and are consistent with previous research showing that black and Hispanic children tend to be diagnosed years later than white children,” said co-author Kate Wallis, MD, MPH, a developmental pediatrician and researcher at CHOP’s PolicyLab who is also studying disparities in referrals for autism services. “This study revealed important limitations and provides us with new knowledge that we can use to make critical improvements to autism screening tools and screening processes, so pediatricians can properly detect and support more children with autism and reduce disparities in diagnosis and care.”

About this neuroscience research article

Media Contacts:
Ben Leach – CHOP
Image Source:
The image is credited to CHOP.

Original Research: Open access
“Accuracy of Autism Screening in a Large Pediatric Network”. Guthrie et al.
Pediatrics doi:10.1542/peds.2019-0925.


Accuracy of Autism Screening in a Large Pediatric Network

Universal screening is recommended to reduce the age of diagnosis for autism spectrum disorder (ASD). However, there are insufficient data on children who screen negative and no study of outcomes from truly universal screening. With this study, we filled these gaps by examining the accuracy of universal screening with systematic follow-up through 4 to 8 years.

Universal, primary care-based screening was conducted using the Modified Checklist for Autism in Toddlers with Follow-Up (M-CHAT/F) and supported by electronic administration and integration into electronic health records. All children with a well-child visit (1) between 16 and 26 months, (2) at a Children’s Hospital of Philadelphia site after universal electronic screening was initiated, and (3) between January 2011 and July 2015 were included (N = 25 999).

Nearly universal screening was achieved (91%), and ASD prevalence was 2.2%. Overall, the M-CHAT/F’s sensitivity was 38.8%, and its positive predictive value (PPV) was 14.6%. Sensitivity was higher in older toddlers and with repeated screenings, whereas PPV was lower in girls. Finally, the M-CHAT/F’s specificity and PPV were lower in children of color and those from lower-income households.

Universal screening in primary care is possible when supported by electronic administration. In this “real-world” cohort that was systematically followed, the M-CHAT/F was less accurate in detecting ASD than in previous studies. Disparities in screening rates and accuracy were evident in traditionally underrepresented groups. Future research should focus on the development of new methods that detect a greater proportion of children with ASD and reduce disparities in the screening process.

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