A population-based developmental surveillance program showed high diagnostic accuracy in identifying autism in a community-based sample of infants, toddlers, and preschoolers, according to new data published online in JAMA Network Open.
Researchers, led by Josephine Barbaro, PhD, of Olga Tennison Autism Research Centre at La Trobe University, Bundoora, Australia, said their findings indicate the benefit of using early autism developmental surveillance from infancy to the preschool period rather than one-time screening.
For the study, maternal and child health nurses in Melbourne were trained to use the Social Attention and Communication Surveillance–Revised (SACS-R) and SACS-Preschool (SACS-PR) tools during well-child checkups at 11-30 months of age and at follow-up (42 months of age). Dr. Barbaro helped develop the SACS tools.
Children identified as being at high likelihood for autism (1-2 years of age: n = 327; 42 months of age: n = 168) and at low likelihood for autism plus concerns (42 months of age: n = 28) were referred by their nurse for diagnostic assessment by the researchers.
Diagnostic accuracy of the SACS-R and SACS-PR was determined by comparing likelihood for autism with children’s diagnostic outcome using clinical judgment based on standard autism assessments.
Researchers included 13,511 children ages 11 months to 42 months. Results indicated the SACS-R with SACS-PR (SACS-R+PR) had very high diagnostic accuracy for early autism detection.
According to the paper, SACS-R showed 83% positive predictive value (95% confidence interval, 0.77-0.87) and 99% estimated negative predictive value (95% CI, 0.01-0.02). Specificity (99.6%; 95% CI, 0.99-1.00) was high, with modest sensitivity (62%; 95% CI, 0.57-0.66). When the SACS-PR 42-month assessment was added, estimated sensitivity grew to 96% (95% CI, 0.94-0.98).
“Its greater accuracy, compared with psychometrics of commonly used autism screening tools when used in community-based samples, suggests that the SACS-R+PR can be used universally for the early identification of autism,” the authors wrote.
According to La Trobe University, the tool is used in 10 other countries around the world – among them China, Singapore, Poland, Japan, New Zealand, Nepal, and Bangladesh.
Early identification is crucial for children on the autism spectrum and their families because it facilitates early diagnosis and can help families get access to supports and services.
About 2% of the world’s population is on the autism spectrum. Some studies report prevalence of 4% or higher, the authors noted.
The authors called attention to a systematic review of universal autism screening in primary care, including the Infant-Toddler Checklist and the Modified Checklist for Autism in Toddlers and various versions. The authors of the review noted that few studies had enough participants to establish population sensitivity, specificity, and positive predictive value. Also, psychometric properties reported were modest and/or wide ranging, putting into question the diagnostic accuracy of the tools.
Dr. Barbaro and colleagues highlighted an advantage the current study offers. “A critical difference in this study was the use of a community-based sample rather than a clinical or high-likelihood sibling sample, which may not be representative of the general population of children on the autism spectrum because child outcomes, cognition, and autism prevalence vary by ascertainment strategy and multiplex or simplex status.”
The authors explained that, in the United States, The U.S. Preventive Services Task Force has said there is not enough evidence to recommend universal autism screening and instead recommends routine general developmental surveillance. The American Academy of Pediatrics recommends developmental surveillance between 9 and 30 months and autism-specific screening at 18 and 24 months because of the benefits of early supports and services.
Dr. Karen Pierce
Karen Pierce, PhD, codirector of the Autism Center of Excellence at University of California, San Diego, said in an interview that she was pleased to see that the researchers were able to identify a high percentage of children on the autism spectrum.
She said, however, that the system proposed in this paper involves a substantial amount of time for training the nurses.
The authors acknowledged that, saying, “there may be instances in which this could be impractical.”
Dr. Pierce said that, in the United States, parent questionnaires are combined with clinical judgment to decide which kids are at risk.
“It doesn’t take very much time to fill out these questionnaires,” she said. “That’s the sticking point. I’m not saying necessarily that it shouldn’t be adopted. It would be very hard, I think, to incorporate into current pediatric practice.”
She said a benefit of the SACS program is more hands-on observation of the child, beyond the parent report, which sometimes can reflect more emotionally how the parent is feeling about the child.
She pointed out it was impressive that the Australian team found virtually no false positives.
The researchers also identified an additional 168 children using the preschool version at 42 months who had actually passed at the earlier checkpoint, using the regular SACS-R.
“This underscores a supercritical point,” Dr. Pierce said. “Just because your child may have gotten screened at 12, 18, 24 months and they pass and everything’s looking great, it doesn’t necessarily mean at some point early in development around age 3 that there [wouldn’t] be some clearer signs of autism.”
She said in her own study, published in JAMA Pediatrics, 24% of their sample tested fine at first but were later identified as having autism.
“It underscores the need for repeat screening,” Dr. Pierce said. “That was a striking finding in this study.”
She also pointed out that the authors talk about the “false dichotomy” between screening and surveillance. “They are saying it doesn’t have to be that way. It can be a combined effort. We can have parents filling out screening tools and we can have more observational sessions with kids during checkups. It doesn’t have to be this rigid line between screening and surveillance. I would completely agree with that.”
Dr. Barbaro reported receiving grants from the Sir Robert Menzies Foundation and the Cooperative Research Centre for Living with Autism (Autism CRC) during the study. Funds are partially distributed to Dr. Barbaro for the background intellectual property. One coauthor reported grants from the Menzies Foundation and Autism CRC during the study. Another coauthor reported receiving salary from Autism CRC during the study. No other disclosures were reported. This work was supported by an Allied Health Sciences start-up grant from the Menzies Foundation and the Cooperative Research Centre for Living with Autism, established and supported under the Australian Government’s Cooperative Research Centres Program. Dr. Pierce reports no relevant financial relationships.