Group items tagged

Pervasive Developmental Disorders, including Autistic Disorder, Asperger Disorder, Pervasive Developmental Disorder Not Otherwise Specified, and Childhood Disintegrative Disorder.

For autistic disorder, Fombonne says: The correlation between prevalence and year of publication was statistically significant and studies with prevalenceover 7/10,000 were all published since 1987. These findings point towards an increase in prevalence estimates in the last 15-20 years.

recent autism surveys have consistently identified smaller numbers of children with AS than those with autism within the same survey.

How much lower is difficult to establish from existing data, but a ratio of 3 or 4 to 1 would appear an acceptable,

We therefore used for subsequent calculations an estimate of 6/10,000 for AS, recognizing the strong limitations of available data on AS.

Eight studies provided data on childhood disintegrative disorder (CDD). Prevalence estimates ranged from 0 to 9.2/100,000.

The upper-bound limit of the associated confidence interval (4.0/100,000) indicates that CDD is a very rare condition, with about 1 case to occur for every 103 cases of autistic disorder.

Current evidence does not strongly support the hypothesis of a secular increase in the incidence of autism but power todetect time trends is seriously limited in existing datasets.

Whilst it is clear that prevalence estimates have gone up over time, this increase most likely represents changes in the concepts, definitions, service availability and awareness of autistic-spectrum disorders in both the lay and professional public.

The possibility that a true change in the underlying incidence has contributed to higher prevalence figures remains, however, to be adequately tested.