Patient-Oriented Evidence That Matters
Autism Screening with Follow-Up Overidentifies Autism Spectrum Disorder
Am Fam Physician. 2020 May 15;101(10):630.
What is the accuracy of a two-step process for universal screening for autism spectrum disorder (ASD) in children ages 16 months to 26 months?
Screening for ASD with the Modified Checklist for Autism in Toddlers with Follow-Up is effective in ruling out ASD in children who screen positive (negative predictive value of 98.6% at 2.2% prevalence). The initial screening identified approximately 10% of toddlers as possibly having ASD, although 94.8% of those children were excluded in the follow-up interview. The positive predictive value was only 14.6%, meaning that 85% of the children who screened positive for ASD were falsely positive. Although some groups recommend universal screening, the U.S. Preventive Services Task Force cites a lack of evidence to support the benefit of early identification. (Level of Evidence = 1b)
This study evaluated the effect of universal screening for autism in primary care at a single hospital using the Modified Checklist for Autism in Toddlers with Follow-Up. Over 4.5 years, they screened 25,999 children between the ages of 16 months and 26 months. At the first screening, almost one in 10 children screened positive (9.1%). However, in the follow-up interview almost all of those children (94.8%) were no longer considered to have ASD, and the final prevalence in the group was 2.2% by four years of age. The resulting positive predictive value was only 14.6%, with a negative predictive value of 98.6% (sensitivity of 38.8%; specificity of 94.9%). In other words, 85% of parents who have a child who initially screens positive will later be told the result was incorrect. The positive predictive value for girls was even lower (7.7%). For children correctly screened as positive, the time to diagnosis was an average of 7.45 months earlier than those who screened negative. Whether this benefit results in faster access to treatment with better results is not known.
Study design: Cohort (prospective)
Funding source: Foundation
Setting: Outpatient (primary care)
Reference: Guthrie W, Wallis K, Bennett A, et al. Accuracy of autism screening in a large pediatric network. Pediatrics. 2019;144(4):pii:e20183963.
Editor's Note: Dr. Shaughnessy is an assistant medical editor for AFP.
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