Socioeconomic Inequality in the Prevalence of Autism Spectrum Disorder: Evidence from a U.S. Cross-Sectional Study

Department of Population Health Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America.
PLoS ONE (Impact Factor: 3.53). 07/2010; 5(7):e11551. DOI: 10.1371/journal.pone.0011551
Source: PubMed

ABSTRACT This study was designed to evaluate the hypothesis that the prevalence of autism spectrum disorder (ASD) among children in the United States is positively associated with socioeconomic status (SES).
A cross-sectional study was implemented with data from the Autism and Developmental Disabilities Monitoring Network, a multiple source surveillance system that incorporates data from educational and health care sources to determine the number of 8-year-old children with ASD among defined populations. For the years 2002 and 2004, there were 3,680 children with ASD among a population of 557,689 8-year-old children. Area-level census SES indicators were used to compute ASD prevalence by SES tertiles of the population.
Prevalence increased with increasing SES in a dose-response manner, with prevalence ratios relative to medium SES of 0.70 (95% confidence interval [CI] 0.64, 0.76) for low SES, and of 1.25 (95% CI 1.16, 1.35) for high SES, (P<0.001). Significant SES gradients were observed for children with and without a pre-existing ASD diagnosis, and in analyses stratified by gender, race/ethnicity, and surveillance data source. The SES gradient was significantly stronger in children with a pre-existing diagnosis than in those meeting criteria for ASD but with no previous record of an ASD diagnosis (p<0.001), and was not present in children with co-occurring ASD and intellectual disability.
The stronger SES gradient in ASD prevalence in children with versus without a pre-existing ASD diagnosis points to potential ascertainment or diagnostic bias and to the possibility of SES disparity in access to services for children with autism. Further research is needed to confirm and understand the sources of this disparity so that policy implications can be drawn. Consideration should also be given to the possibility that there may be causal mechanisms or confounding factors associated with both high SES and vulnerability to ASD.

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    • "), how and when autism can be diagnosed (e.g., Lord et al. 1997; Luyster et al. 2009), the increasing prevalence of autism diagnoses and factors that may contribute to this (e.g., Blumberg et al. 2013; Kim et al. 2011), ethnic disparities in autism diagnoses in the United States and likely contributions of socioeconomic factors to these disparities (e.g., Durkin et al. 2010; Mandell et al. 2007), the higher prevalence of autism among males and the possibility that diagnostic measures may be less effective in detecting autism in females (e.g., Baron-Cohen et al. 2009), and how cultural factors including stigma may influence rates of diagnosis internationally (e.g., Elsabbagh et al. 2012; Kim et al. 2011). After introducing common traits observed among people with autism and emphasizing that each individual with autism is unique (e.g., Wing 1988), the training discussed associations between giftedness and autistic traits in the general population (e.g., Vital et al. 2009), and the heterogeneity of intelligence in autism (e.g., Bölte et al. 2009). "
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    ABSTRACT: Background: College students with ASD may face lack of understanding from their campus communities. While a recent closed-ended survey of campus knowledge of ASD revealed more correct than incorrect responses, participants often indicated that there is only one effective intervention for autism, that autism is caused by vaccines, and that people with autism can’t live independently (Tipton & Blacher, 2013). Although closed-ended surveys allow comparison across studies, they may scaffold appropriate responses. Qualitative coding of definitions of autism provided by middle-school children revealed largely accurate but sparse responses that often lacked reference to the core symptoms of autism, particularly restricted interests and repetitive behaviors (Campbell et al., 2011). Semi-structured interviews revealed that adults often view people with ASD as learning disabled and incapable of living independently (Huws & Jones, 2010). Using a mixed-methods approach, we examined knowledge of autism among college students, as well as potential benefits of an online training about autism. Objectives: 1) Examine open-ended definitions of autism by college students. 2) Evaluate effects of an online training on conceptions of autism. Methods: Participants were recruited for an online training about ASD primarily from a psychology subject pool. Participants (N= 171) completed a pre-test (consisting of open-ended and multiple choice questions), the training, and a post-test. Open-ended responses were coded into non-mutually exclusive categories by independent coders after they achieved reliability (greater than 80% agreement on at least 20% of the sample). Not all coding categories are reported. Results: Baseline Knowledge of ASD: What is ASD? 110 responses were coded “communication issues”, 105 “social issues”, 77 “disorder”, 57 “restricted/repetitive interests”, 51 “childish”, 38 “diversity”, 38 “cognitive issues”, 28 “brain issues” and 21 “sensory issues.” What are two challenges adults with autism face? 99 responses were coded “social”, 87 “independence”, 34 “communication”, 21 “discrimination”, 19 “other/don’t know”, and 15 “cognitive". What does the future hold for people with ASD? 47 responses were coded “other/don’t know”, 35 “treatments”, 27 “opportunities”, 19 “cure”, 4 “employment”, and 1 “college”. Changing Conceptions of ASD: What does the future hold for people with ASD? After the training, responses coded “college” (35) and “employment” (43) increased. What are three techniques for teaching people with ASD? Before the training, 48 responses were coded “visual”, 41 “structured”, and 21 “individualized” After the training, 92 responses were coded “visual”, 57 “individualized”, and 55 “structured.” Closed-ended responses suggest that the training increased understanding of DSM-5 criteria, gender and ethnic differences in diagnosis, links between giftedness and autistic traits in the general population, interest in friendship among people with ASD, and variability in desire for a cure for autism (ps < .001). Conclusions: These results suggest that college students have greater understanding of the core difficulties associated with autism than middle-school students. However, both populations conflate autism with cognitive delays and are more aware of social symptoms than restricted/repetitive interests. The online training altered conceptions of autism. As Tipton and Blacher noted (2013), more widespread knowledge about diversity in ASD may facilitate the transition into college for students with ASD.
    2014 International Meeting for Autism Research; 05/2014
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    • "It is notable that the study also indicates that Black and Hispanic children are more likely to live in areas of poverty, which suggests that Black and Hispanic children are systematically less likely to be diagnosed with autism. The implication is that the lower overall prevalence of autism among these population groups is correlated to the lack of appropriate medical attention because areas of higher poverty are less likely to offer high quality medical services (Durkin et al. 2010; Mandell et al., 2009). "
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    ABSTRACT: The purpose of this study is to explore the knowledge and attitudes about autism spectrum disorders among Hispanics in the Southwest. The study will also examine perceived barriers in obtaining resources and preferences in accessing health care. Participants (N = 169) were surveyed using the Autism Awareness Survey, which was developed specifically for this research. Significant differences were found between individuals with high acculturation and low acculturation in exposure to autism, knowledge about autism, perceived barriers to obtaining resources and health care, and attitudes towards people with autism. Additionally, the findings also suggest that although the surveyed population was knowledgeable about the symptoms associated with autism, less well known is the etiology and course of the disorder. The research underscores the serious need for both Spanish educational resources and Spanish-speaking health care providers to address the needs of Hispanics with regards to autism, especially with individuals with low levels of acculturation.
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    • "In addition, Durkin et al. (2010) reported a differential socioeconomic (SES) gradient in ASD prevalence by the presence or absence of ID; SES acts as a stronger risk factor for ASD-ID compared to ASD+ID [3]. Because we expect SES to vary spatially and be a spatial confounder, analyzing ASD without respect to ID may mask the true spatial patterning of disease. "
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    ABSTRACT: Background The causes of autism spectrum disorders (ASD) remain largely unknown and widely debated; however, evidence increasingly points to the importance of environmental exposures. A growing number of studies use geographic variability in ASD prevalence or exposure patterns to investigate the association between environmental factors and ASD. However, differences in the geographic distribution of established risk and predictive factors for ASD, such as maternal education or age, can interfere with investigations of ASD etiology. We evaluated geographic variability in the prevalence of ASD in central North Carolina and the impact of spatial confounding by known risk and predictive factors. Methods Children meeting a standardized case definition for ASD at 8 years of age were identified through records-based surveillance for 8 counties biennially from 2002 to 2008 (n=532). Vital records were used to identify the underlying cohort (15% random sample of children born in the same years as children with an ASD, n=11,034), and to obtain birth addresses. We used generalized additive models (GAMs) to estimate the prevalence of ASD across the region by smoothing latitude and longitude. GAMs, unlike methods used in previous spatial analyses of ASD, allow for extensive adjustment of individual-level risk factors (e.g. maternal age and education) when evaluating spatial variability of disease prevalence. Results Unadjusted maps revealed geographic variation in surveillance-recognized ASD. Children born in certain regions of the study area were up to 1.27 times as likely to be recognized as having ASD compared to children born in the study area as a whole (prevalence ratio (PR) range across the study area 0.57-1.27; global P=0.003). However, geographic gradients of ASD prevalence were attenuated after adjusting for spatial confounders (adjusted PR range 0.72-1.12 across the study area; global P=0.052). Conclusions In these data, spatial variation of ASD in central NC can be explained largely by factors impacting diagnosis, such as maternal education, emphasizing the importance of adjusting for differences in the geographic distribution of known individual-level predictors in spatial analyses of ASD. These results underscore the critical importance of accounting for such factors in studies of environmental exposures that vary across regions.
    Environmental Health 10/2012; 11(1):80. DOI:10.1186/1476-069X-11-80 · 2.71 Impact Factor
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