Early Identification of Toddlers with Autism Spectrum Disorder at 18-24 Months of Age By the Screening Tools for Autism in Two-Year-Olds Taiwan Version (T-STAT)

Background: Autism spectrum disorder (ASD) is characterized by impaired social interaction and communication, as well as restricted and repetitive behavior and interest. Over past decade, some studies reported that prevalence of ASD has increased markedly. Previous studies reported that early intervention improved outcomes for toddlers with ASD (Dawson et al., 2010; Landa et al., 2011). The benefits of early intervention highlighted the importance of earlier identification of toddlers with ASD. The American Academy of Pediatrics (AAP) has recommended that all infants receive universal screening for autism less than 24 months old (Johnson et al., 2007). However, the diagnosis of ASD is still often delayed because diverse factors, for example, limitations in utility of screening instruments.

Objectives: There are few level 2 screening tools to distinguish ASD from other developmental disorders for toddlers before 24 months. It would weaken work of early diagnosis and early intervention for children with ASD. Therefore, the current research, there are two studies to test utility of using the Screening Tools for Autism in Two-Year-Olds, Taiwan version (T-STAT) (Chiang et al., 2012, 2013) for toddlers with ASD from 18 to 24 months of age.

Methods: The T-STAT is a 12 items interactive autism-specific screening tool, including four behavioral domains: play (2 items), requesting (2 items), joint attention (4 items) and imitation (4 items). Within both play and requesting, if a toddler fails one item, he would receive a score of 0.50. Within both joint attention and imitation, if a toddler fails one item, he would receive a score of 0.25. The scores of four domains are from 0 to 1. The scores of four domains are summed, obtaining a total T-STAT scores which from 0 to 4.

Results: Study 1, there are 30 toddlers from 18 to 24 months of age, including 15 toddlers with ASD and 15 toddlers with developmental delayed (DD). Using signal detection procedures, the optimal cutoff of the total T-STAT score was decided. The results revealed that 2.25 or 2.50 was the best cutoff. Using the 2.25 of total T-STAT score as cutoff, the sensitivity and specificity are .93 and .93, respectively. In addition, positive predicative value (PPV) is .93 and negative predicative value (NPV) is .93. Using the 2.50 of total T-STAT score as cutoff, the sensitivity and specificity are .87 and .93, respectively. In addition, PPV is .93 and NPV is .88. Study 2, there are 70 toddlers from 18 to 24 months of age, including 33 toddlers with ASD and 37 toddlers with DD. Using the 2.25 as cutoff, the sensitivity and specificity are .91 and .89, respectively. In addition, PPV is .88 and NPV is .92. Using the 2.50 as cutoff, the sensitivity and specificity are .91 and .95, respectively. In addition, PPV is .94 and NPV is .95.

Conclusions: The results of this current research showed that the T-STAT is a promising good tool to differentiate the toddlers with ASD and toddlers with DD from 18 to 24 months of age.