Predictors of Developmental Outcome in 4- to 6-Year-Olds With Developmental Disability

Studies on the early trajectories of developmental disability (DD) are limited. This study aimed to evaluate the diagnostic stability and developmental trajectories of autism spectrum disorder (ASD) and intellectual disability (ID), and to determine baseline clinical characteristics that affect future diagnosis.

We analyzed 192 children who were referred for possible DD through retrospective chart review. Clinical diagnosis was assessed once at baseline, aged 2-4, and at follow-up, aged 4-6. The participants' developmental profiles were measured by Psychoeducational Profile-Revised (PEP-R), Vineland Social Maturity Scale (VSMS), Beery-Buktenica Developmental Test of Visual Motor Integration (VMI), and Childhood Autism Rating Scale (CARS).

On comparing the diagnostic change, 5% of children were no longer diagnosed as ASD, and 13% of children were no longer diagnosed as ID at follow-up. Trajectories of developmental profiles were compared between children with and without ID at follow-up, and significant time-by-group interaction were observed in PEP-R (p<0.001), VSMS (p<0.001), and VMI (p=0.003) scores, indicating that children without ID at follow-up showed significant improvement over time compared to children with ID. ASD diagnosis (p<0.001) and CARS score (p=0.007) at baseline were significantly associated with ASD at follow-up, while VSMS score (p=0.004) and VMI score (p=0.019) at baseline were significantly associated with ID at follow-up.

A subset of children lost their diagnosis at follow-up, and such diagnostic change was significantly more common in ID compared to ASD. Baseline autism symptomatology was related to ASD at follow-up, and baseline adaptive and visuo-motor function was related to ID at follow-up.