Prevalence of Co-occurring Medical and Behavioral Conditions/Symptoms Among 4- and 8-Year-Old Children with Autism Spectrum Disorder in Selected Areas of the United States in 2010.

We compared the prevalence of various medical and behavioral co-occurring conditions/symptoms between 4- and 8-year-olds with autism spectrum disorder (ASD) from five sites in the Autism and Developmental Disabilities Monitoring Network during the 2010 survey year, accounting for sociodemographic differences. Over 95% of children had at least one co-occurring condition/symptom. Overall, the prevalence was higher in 8- than 4-year-olds for 67% of co-occurring conditions/symptoms examined. Further, our data suggested that co-occurring conditions/symptoms increased or decreased the age at which children were first evaluated for ASD. Similarly, among the 8-year-olds, the prevalence of most co-occurring conditions/symptoms was higher in children with a previous ASD diagnosis documented in their records. These findings are informative for understanding and screening co-occurring conditions/symptoms in ASD.

Brief Report: Estimated Prevalence of a Community Diagnosis of Autism Spectrum Disorder by Age 4 Years in Children from Selected Areas in the United States in 2010: Evaluation of Birth Cohort Effects.

We compared early-diagnosed autism spectrum disorder (ASD) (defined as diagnosis by age 4 years) between the 2002 and 2006 birth cohorts, in five sites of the Autism and Developmental Disabilities Monitoring Network. In the 2002 cohort, the prevalence/1000 of early-diagnosed ASD was half the 8-year-old prevalence (7.2 vs. 14.7, prevalence ratio [PR] 0.5 [0.4-0.6]). Overall, the prevalence of early-diagnosed ASD did not differ between birth cohorts (PR 1.1 [0.9-1.3]). However, in three sites with complete case ascertainment, the prevalence of early-diagnosed ASD was higher for those born in 2006 versus 2002 (PR 1.3 [1.1-1.5]), suggesting possible improvement in early identification. The lack of change in two sites may reflect less complete case ascertainment. Studies in more recent cohorts are needed.