Epidemiological studies have found that autism is not predicted by race, ethnicity, or socioeconomic status (Fombonne,2003; 2005; 2007), but studies of administrative identification have found differences in identification of autism according to race (e.g., Mandell et al., 2010). Travers, et al. (2009) examined national population data from public education for trends in identification from 1997 to 2004, finding persistent under-identification of autism among Hispanic and Native American/Alaska Native students when compared to White students. They also discovered a trend from over- to under-identification of Black students with autism from 1997 to 2004. However, it was unclear if national trends in the U.S. were reflective trends among regions of the U.S. as well as individual states. A thorough examination of the patterns and trends in prevalence rates by race and across states was an important next step in this line of research.
This study examined trends in state-level administrative identification of autism under the U.S. Individuals with Disabilities Education Act (IDEA). The purpose was to determine if and to what extent state-level administrative prevalence of autism differed by race from 2000 to 2007.
Prevalence rates and odds ratios were calculated for each U.S. state using enrollment count data from the IDEA Annual Reports to Congress and National Center for Education Statistics for years 2000 and 2007. We used logistic regression analysis, with confidence levels set at 95%, to understand difference in prevalence of autism according to race as well as changes in the prevalence by race over time.
Results indicated increases in administrative prevalence of autism for all racial groups from 2000 to 2007, but increasing under-identification of Black and Hispanic students in 2007 compared to White students. Variability existed in the identification of autism among Black and Hispanic students across states over time.
We found a) the odds of being identified with autism was predicted by year and b) a nearly three-fold increase in prevalence between 2000 to 2007. When we analyzed differences by race, we found odds ratios for Black students that decreased over time and odds ratios for Hispanic students that remained consistently lower than their White counterparts. We found substantial differences in prevalence rates by state as well as by racial category. Prevalence rates for Hispanic and Black students were lower, sometimes substantially, than prevalence rates for White students in most states. We also found prevalence rates of autism in 39 states for year 2007 that were lower than the 2006 epidemiological prevalence rates reported by the CDC. As expected, the prevalence rates for all three racial groups and all states increased over time. However, we found that the disparity between White and minority students increased over time. We found that the states that over-identified autism among Black and Hispanic students in 2000 had under-identified them in 2007. Furthermore, nearly every state that had proportional representation of students in 2000 under-identified Black and Hispanic students in 2007.
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See more of: Prevalence, Risk factors & Intervention