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We examined prevalence of diagnosed autism spectrum disorder (ASD) and age at diagnosis according to child's race/ethnicity and primary household language. From the 2009-2010 National Survey of Children with Special Health Care Needs, we identified 2729 3-17-year-old US children whose parent reported a current ASD diagnosis. We compared ASD prevalence, mean diagnosis age, and percentage with later diagnoses (≥5 years) across racial/ethnic/primary household language groups: non-Hispanic-white, any language (NHW); non-Hispanic-black, any language (NHB); Hispanic-any-race, English (Hispanic-English); and Hispanic-any-race, other language (Hispanic-Other). We assessed findings by parent-reported ASD severity level and adjusted for family sociodemographics. ASD prevalence estimates were 15.3 (NHW), 10.4 (NHB), 14.1 (Hispanic-English), and 5.2 (Hispanic-Other) per 1000 children. Mean diagnosis age was comparable across racial/ethnic/language groups for 3-4-year-olds. For 5-17-year-olds, diagnosis age varied by race/ethnicity/language and also by ASD severity. In this group, NHW children with mild/moderate ASD had a significantly higher proportion (50.8 %) of later diagnoses than NHB (33.5 %) or Hispanic-Other children (18.0 %). However, NHW children with severe ASD had a comparable or lower (albeit non-significant) proportion (16.4 %) of later diagnoses than NHB (37.8 %), Hispanic-English (30.8 %), and Hispanic-Other children (12.0 %). While NHW children have comparable ASD prevalence and diagnosis age distributions as Hispanic-English children, they have both higher prevalence and proportion of later diagnoses than NHB and Hispanic-Other children. The diagnosis age findings were limited to mild/moderate cases only. Thus, the prevalence disparity might be primarily driven by under-representation (potentially under-identification) of older children with mild/moderate ASD in the two minority groups. [ABSTRACT FROM AUTHOR]

The prevalence of autism spectrum disorders (ASD) from the 2007 National Survey of Children's Health (NSCH) was twice the 2003 NSCH estimate for autism. From each NSCH, we selected children born in the US from 1990 to 2000. We estimated autism prevalence within each 1-year birth cohort to hold genetic and non-genetic prenatal factors constant. Prevalence differences across surveys thus reflect survey measurement changes and/or external identification effects. In 2003, parents were asked whether their child was ever diagnosed with autism. In 2007, parents were asked whether their child was ever diagnosed with an ASD and whether s/he currently had an ASD. For the 1997-2000 birth cohorts (children aged 3-6 years in 2003 and 7-10 years in 2007), relative increases between 2003 autism estimates and 2007 ASD estimates were 200-600 %. For the 1990-1996 birth cohorts (children aged 7-13 years in 2003) increases were lower; nonetheless, differences between 2003 estimates and 2007 'ever ASD' estimates were >100 % for 6 cohorts and differences between 2003 estimates and 2007 'current ASD' estimates were >80 % for 3 cohorts. The magnitude of most birth cohort-specific differences suggests continuing diagnosis of children in the community played a sizable role in the 2003-2007 ASD prevalence increase. While some increase was expected for 1997-2000 cohorts, because some children have later diagnoses coinciding with school entry, increases were also observed for children ages ≥7 years in 2003. Given past ASD subtype studies, the 2003 'autism' question might have missed a modest amount (≤33 %) of ASDs other than autistic disorder. [ABSTRACT FROM AUTHOR]