|dc.description.abstract||Early diagnosis of autism spectrum disorders (ASD) is crucial because early identification can lead to early intervention, which has been shown to improve the outcome of children diagnosed with ASD. This study explored the current mean age of diagnosis of Autism and Pervasive Developmental Disorder, NOS in the United States. Analysis of variance was employed to determine whether average age of diagnosis of children with Autism and Pervasive Developmental Disorder NOS differs in the four regions in the United States. Linear regression analyses were performed to determine which of the following factors predict age of diagnosis: the child’s ethnicity, whether the child has an older typically developing sibling, whether the child has an older sibling who had/has a developmental delay other than autism, whether the child has an older sibling who has been diagnosed with autism, whether the child was first diagnosed with another disorder, the type of first symptoms to cause concern, whether the child was referred to ECI, whether the child switched pediatricians, whether the child’s pediatrician conducted regular developmental screenings, whether the child’s pediatrician conducted a screening specific to autism, reaction of pediatrician if parent raised concerns regarding child’s development, whether the child was covered by health insurance, annual household income, and parents’ level of education.
Potential participants were recruited with the assistance of the Interactive Autism Network (IAN) Research Database at the Kennedy Krieger Institute and Johns Hopkins Medicine in Baltimore, sponsored by the Autism Speaks Foundation. Participants were selected from a pool of participants who have registered with IAN, who have agreed to participate in autism research, and whose children met the study criteria. The potential participants were sent a recruitment letter via email by IAN research personnel, which included a link to the on-line survey. The study description and a link to the survey were also posted on the IAN Community Research Opportunities Bulletin Board.
A sample size of 654 participants was used for data analysis. Current age of diagnosis in months of autistic disorder and PDD-NOS in the United States was 37.78, and SD=16.269. Due to violations of normality assumptions for age of diagnosis, a logarithm transformation was used (M=1.54 and SD=.166). Results of a one-way ANOVA indicated differences in age of diagnosis among the four regions in the United States F (3, 650) = 7.618, p=.01). Tukey’s post hoc comparisons of the groups indicated that the mean log base 10 age of diagnosis in the Midwest (M=1.59) was significantly later than in the Northeast (M=1.5152, p=.000) and South (M=1.5219, p=.000). Results of a Pearson Correlation indicated a significant negative correlation (r=-.409, n=654, p=.000) between date of birth and age of diagnosis, with later birthdays being associated with lower age of diagnosis. Regression results were statistically significant, F(25, 620)=7.549, p<.001, R2=.233. Having autistic older sibling/s, being referred to ECI, and having a pediatrician who performed an in-depth screening in response to parent concerns, were negatively correlated with the logarithm of age of diagnosis, while having first symptoms of non-autism specific behavioral difficulties, being given a non-ASD diagnosis prior to ASD diagnosis and switching pediatricians during first five years of life, were positively correlated with the logarithm of age of diagnosis.||