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Poster #182 - Incremental Utility of 24-Month Autism Spectrum Disorder Screening After Negative 18-Month Screening

Fri, March 22, 7:45 to 9:15am, Baltimore Convention Center, Floor: Level 1, Exhibit Hall B

Integrative Statement

Introduction. Children with Autism Spectrum Disorder (ASD) benefit from early, intensive ASD-specific intervention (Anderson, Liang, & Lord, 2014; MacDonald, Parry-Cruwys, Dupere, & Ahearn, 2014; Rogers & Vismara, 2008), yet provision of these services is contingent upon early diagnosis. The American Academy of Pediatrics (AAP) recommends screening at 18 and 24 months; however, to date, there is no research regarding the incremental utility of repeated screening after a negative (i.e., not at-risk) screening at 18 months. The present study aimed to (1) identify cases of ASD detected at 24 months after a negative 18-month screening (i.e., Catch-24 Group) and (2) compare Catch-24 children to those detected by 18-month screening (i.e., Early Diagnosis Group).
Methods. Participants were screened with either the Modified Checklist for Autism in Toddlers with Follow-Up (M-CHAT/F) or its revision, the M-CHAT-R/F, at their 18-month pediatric well-child care visit (n = 19,685), or at both their 18- and 24-month well-child care visits (n = 7,993; 7,781 of these children screened negative at 18 months). Children who screened positive (i.e., at-risk for ASD) were offered a free evaluation to assess developmental level, adaptive skills, and ASD symptoms.
Results. Of the 7,781 children who screened negative at 18 months and were rescreened at 24 months, 0.4% (n = 32) screened positive at 24 months. Ten of these children, or 0.1% of the entire rescreening sample, received an ASD diagnosis (i.e., Catch-24 Group). Overall, of the children who screened negative at 18 months and positive at 24 months, who were subsequently evaluated (n = 20), 80% received a developmental diagnosis warranting intervention (including the 10 toddlers with ASD), and only 20% were typically developing. The Catch-24 children had greater ASD severity (Autism Diagnostic Observation Schedule calibrated severity score M = 8.00, SD = 1.31), with a small to medium effect, (t(186) = -2.73, p = .01, η2 = .04), than the Early Diagnosis children (M = 6.04, SD = 2.01). However, groups demonstrated comparable cognitive and adaptive abilities. Similarly, groups did not differ on child gender, race/ethnicity, maternal education, or annual household income.
Discussion: Despite a relatively low yield of ASD cases at 24 months after negative 18-month screening, this study supports the current AAP recommendations that all children be routinely screened at both their 18- and 24-month well-child care visits, in order to maximize identification of at-risk toddlers. The opportunity to identify additional children who would likely benefit from early intervention, in our view, outweighs the risks and possible inconveniences of executing this repeated screening procedure.

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