Children with autism missed by early screening show measurable differences at screening age

1. Children who pass screening for autism spectrum disorders (ASD) at 18 months, but who later go on develop ASD display delays and atypical behaviors in social, communicative and motor domains at time of screening, as measured by instruments beyond the standard screening.

2. Females missed by early ASD screening showed a different profile of measured traits than males missed by screening.

Evidence Rating Level: 2 (Good)

Study Rundown: Screening for ASD allows identification of children who will benefit critical early interventions shown to improve outcomes in ASD. However, the heterogeneity of ASD across sex and age pose a challenge to developing instruments for screening. Currently, the most widely used screening for ASD is the Modified Checklist for Autism in Toddlers (M-CHAT). In this study, authors examined the characteristics of children who screened negative on the M-CHAT at 18 months, but who later received an ASD diagnosis (false-negative). In comparing this false-negative group to children who screened negative and did not go on to develop ASD (true-negative), the authors found that false-negative children differed on developmental and temperamental features also measured at 18 months. Overall, while this study needs validation, as it’s findings about the sensitivity and positive predictive value of the M-CHAT is discordant with existing literature, the study’s approach of co-collected data on multiple instruments allows specific analysis of how current screening for ASD could be improved. The major implication of this study is that current ASD screening may miss particular children with ASD, and that further work in developing better screening, such as including some factors measured by the authors, or sex-specific screening tools, may help prevent false-negative screens.

Click to read the study, published today in Pediatrics

Click to read an accompanying editorial, published today in Pediatrics

Study author, Dr. Roald Øien, talks to 2 Minute Medicine: Department of Psychology, University of Tromsø – The Arctic University of Norway, Tromsø, Norway.

“The article contributes to our understanding that most children with a prospective diagnosis of ASD pass on 18-month screening, but they still show atypicalities in development that might not be specific to Autism Spectrum Disorders. Interestingly, females with a later diagnosis of ASD show less social fearfulness, which could make them seem less socially avoidant than males.” 

Relevant Reading: Autism Spectrum Disorder: Primary Care Principles

In-Depth [retrospective cohort]: The study sample was derived from the Norwegian Mother and Child Cohort Study, with a specific sub-sample of 68 197 M-CHAT screen-negative cases. Of those, there were 228 cases of ASD later diagnosed. M-CHAT screening, as well as portions of the Ages and Stages Questionnaire (ASQ) and the Emotionality Activity Sociability Temperament Survey (EAS), were completed at 18 months of age for each child. Univariate ANOVAs compared across eventual diagnosis (ASD vs no ASD) and sex (male vs female) for domain scores from the ASQ and EAS measures. Lower scores by the false negative group on ASQ measures were found in all four domains (social, communication, fine motor, and gross motor, all p<0.001), and interactions between sex and eventual diagnosis group were found in all but the fine motor category. In the EAS measures, lower scores by the false negative group were noted in the sociability (p<.001) and activity domains (p<.036). No differences were noticed across eventual diagnosis groups or sex for emotionality. Although there was no difference between eventual diagnosis group or sex in the shyness domain, there was a robust diagnosis by sex interaction (p=.001). The post-hoc analysis showed that false negative girls were rated as less shy than girls in the true negative group (p=.035), or the boys in the false negative group (p=.017).

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