A Prospective Study of Toddlers with ASD: A Short-Term Diagnostic Stability and Developmental Outcome

Background: Recent literature demonstrated that the number of toddlers referred for a differential diagnosis of autism spectrum disorders (ASD), short-term stability of the early diagnosis in this cohort lack in Taiwan.

Objectives: The purpose of the study was to report the diagnostic stability and the developmental outcomes in the children with ASD at age 2 as Time 1 and followed them at age 4 in Taiwan.

Methods: Eighty-six children were diagnosed with ASD (n = 44) or developmental disorder (DD)(n = 42) between 24 and 36 months (Time 1, mean = 28.97 months, SD = 4.1 months) and re-diagnosed between 42 and 55 months (Time 2, mean = 47.53 months, SD = 4.2 months). Diagnoses based on clinical judgment using DSM-IV and Autism Diagnostic Observation Scales (ADOS, Lord, et al, 1999) in Time 1 and added Autism Diagnostic Interview-Revised (ADI-R, Lord, et al, 1994) at time 2.

Results: First, according to clinical judgment, the consistency between two time point in autistic disorder (AD), pervasive developmental disorder-NOS (PDDNOS) and DD were 78.9%, 44.4% and 89.7%, respectively. Regarding ADOS diagnosis at two time point, the consistency in AD, PDDNOS, and DD were 71.3%, 31.2% and 91.4%, respectively. At time 1, the consistency between clinical judgment and ADOS in AD, PDDNOS and DD were 92.3%, 54.1% and 94.2%, respectively. At time 2, the steadiness between clinical judgment and ADOS in AD, PDDNOS and DD were 94.6%, 70.5% and 95.2%, respectively. While using ASD and non-ASD as categorization, the consistency between clinical judgment and ADOS were 95.4% and 84.6% at time 1, and 95.4% and 97.6% at time 2 respectively. Second, at time 1, the proportions of DQ>70 in the children with AD, PDD-NOS and DD were 28.6%, 44.4% and 54.8% respectively. However, the rate of DQ>70 in the children with AD, PDD-NOS and DD were generally increased to 47.6%, 56.1% and 61.8%. The type and duration of early intervention were associated with the developmental outcome.

Conclusions: Stability of early diagnosis in ASD indicated an acceptable level at age 2 and more consistent at age 4 based on DSM-IV. The quality and quantity of early intervention were related to the cognitive outcome. Future studies should use DSM-5 for exploring the issue in diagnostic stability and developmental outcome.