Prevalence and Characteristics of Children with Autism Spectrum Disorders in South Carolina

Purpose

The purpose of this study was to determine the prevalence of autism spectrum disorders (ASDs) and associated characteristics among children in South Carolina (SC). ASDs include autistic disorder, Asperger's disorder, and pervasive developmental disorder - not otherwise specified.

Methods

The SC Autism and Developmental Disabilities Monitoring (ADDM) program is part of the CDC's on-going ADDM Network, a multi-state active, multiple-source, records-based surveillance program among children aged 8 years in specified study years. SC's catchment area consists of 21 counties in the coastal half of the state, utilizing records from 41 school districts, 21 SC Department of Disabilities and Special Needs Boards, and clinics at the area's two major universities. Cases from the first two study years (2000 and 2002) have been combined for this analysis.

Results

A total of 296 children met criteria for ASD, yielding a prevalence of 6.2 per 1000. The racial distribution of cases was similar to that of 8 year olds in the catchment area: 50% white, 42% black, 2% other, 6% unknown. Males were more commonly affected than females (2.9:1); however, females were more often cognitively impaired than males (4.1:1, male to female, in the average/above average range, 1.8:1 in the moderate/severe/profound range). Regression (loss of previously acquired skills) was noted in 19% of cases and an additional 3% experienced a developmental plateau. In addition to social and communication delays and atypical behaviors, other commonly observed features among cases were: hyperactivity/attention problems (82%), delayed motor functioning (62%), abnormality in mood/affect (55%), abnormality in eating/drinking/sleeping (54%), temper tantrums (53%), argumentative/oppositional/defiant behavior (51%). Developmental concerns were noted before 36 months in 85% of cases, with earliest evaluation with an ASD diagnosis at median 57 months. Seventy-eight percent of cases were served in special education.

Conclusion

Because this is an ongoing study, these estimates establish a baseline for assessment of changes in ASD prevalence over time.

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