Verbal skills were assessed at approximately ages 2, 3, 5, and 9 years for 206 children with a clinical diagnosis of autism (n = 98), pervasive developmental disorders-not otherwise specified (PDD-NOS; n = 58), or nonspectrum developmental disabilities (n = 50). Growth curve analyses were used to analyze verbal skills trajectories over time. Nonverbal IQ and joint attention emerged as strong positive predictors of verbal outcome. The gap between the autism and other 2 groups widened with time as the latter improved at a higher rate. However, there was considerable variability within diagnostic groups. Children with autism most at risk for more serious language impairments later in life can be identified with considerable accuracy at a very young age, while improvement can range from minimal to dramatic.
Autistic Disorder/epidemiology , Cognition Disorders/epidemiology , Verbal Behavior , Attention , Autistic Disorder/diagnosis , Child , Child, Preschool , Cognition Disorders/diagnosis , Female , Humans , Language , Male , Nonverbal Communication , Observer Variation , Prevalence , Psychometrics , Severity of Illness Index
CONTEXT: Autism represents an unusual pattern of development beginning in the infant and toddler years. OBJECTIVES: To examine the stability of autism spectrum diagnoses made at ages 2 through 9 years and identify features that predicted later diagnosis. DESIGN: Prospective study of diagnostic classifications from standardized instruments including a parent interview (Autism Diagnostic Interview-Revised [ADI-R]), an observational scale (Pre-Linguistic Autism Diagnostic Observation Schedule/Autism Diagnostic Observation Schedule [ADOS]), and independent clinical diagnoses made at ages 2 and 9 years compared with a clinical research team's criterion standard diagnoses. SETTING: Three inception cohorts: consecutive referrals for autism assessment to (1) state-funded community autism centers, (2) a private university autism clinic, and (3) case controls with developmental delay from community clinics. PARTICIPANTS: At 2 years of age, 192 autism referrals and 22 developmentally delayed case controls; 172 children seen at 9 years of age. MAIN OUTCOME MEASURES: Consensus best-estimate diagnoses at 9 years of age. RESULTS: Percentage agreement between best-estimate diagnoses at 2 and 9 years of age was 67, with a weighted kappa of 0.72. Diagnostic change was primarily accounted for by movement from pervasive developmental disorder not otherwise specified to autism. Each measure at age 2 years was strongly prognostic for autism at age 9 years, with odds ratios of 6.6 for parent interview, 6.8 for observation, and 12.8 for clinical judgment. Once verbal IQ (P = .001) was taken into account at age 2 years, the ADI-R repetitive domain (P = .02) and the ADOS social (P = .05) and repetitive domains (P = .005) significantly predicted autism at age 9 years. CONCLUSIONS: Diagnostic stability at age 9 years was very high for autism at age 2 years and less strong for pervasive developmental disorder not otherwise specified. Judgment of experienced clinicians, trained on standard instruments, consistently added to information available from parent interview and standardized observation.
Autistic Disorder/diagnosis , Developmental Disabilities/diagnosis , Adult , Age Factors , Autistic Disorder/epidemiology , Child , Child, Preschool , Cohort Studies , Comorbidity , Developmental Disabilities/epidemiology , Humans , Intelligence , Interview, Psychological , Language Development , Language Development Disorders/diagnosis , Language Development Disorders/epidemiology , North Carolina/epidemiology , Odds Ratio , Parents/psychology , Prevalence , Prognosis , Prospective Studies , Psychiatric Status Rating Scales , Reproducibility of Results , Socialization
