Convergent and Divergent Validity of the Early Video Guided Autism Screener (EVAS) in a Clinically-Referred Sample
Objectives: To examine the construct validity (i.e., divergent and convergent validity) of the EVAS in a clinically referred sample, relative to the CBCL, which shows growing evidence as a potential ASD screening tool.
Methods: Sample of 178 children aged 18-48 months (83.7% male, 52.2% White, Mean age = 33.24 months, SD = 8.43 months) referred to an autism specialty center for diagnostic evaluation due to concerns for possible ASD. Parents completed the EVAS and CBCL online during the clinic intake process prior to their diagnostic visits. A clinical best estimate (CBE) was assigned by the diagnosing clinician following the evaluation.
Results: To account for multiple comparisons, a Bonferroni correction was applied to evaluate differences between the EVAS cut-off and each CBCL syndrome and DSM-oriented scale (.05/13 = .0038). Using this correction, only the CBCL Withdrawn (t(176) = 3.18, p = .002) and PDD (t(176) = 3.23, p < .001) subscales differed according to EVAS screening results (See Figure 1). Children who screened positive on the EVAS had T scores over 1 SD higher on the Withdrawn and PDD scales than children who screened negative on the EVAS, suggesting convergent validity of EVAS screening results. Children who screened positive and negative on the EVAS were similar in terms of all other CBCL scales, child age, and child race (all p> .0038), suggesting evidence for divergent validity. See Table 1 for a summary of results.
Conclusions: Results provide evidence for construct validity of the EVAS, suggesting it is a valid tool to measure ASD-related concerns. Importantly, results suggest that the EVAS items are specific to ASD, rather than associated comorbidities (e.g., attention or affective concerns). Thus, the EVAS has strong potential as an ASD-specific screening tool.
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