The incidence of autism spectrum disorder (ASD) refers to the number of new cases identified in a specified time period. The prevalence of ASD refers to the number of individuals who are living with ASD in a given time period.
Completely accurate numbers are difficult to obtain due to possible under- or overidentification, lack of a biological marker, variations in the quality and quantity of behavioral information in records, and other factors (Mulvihill et al., 2009).
In 2014, estimated ASD prevalence was 16.8 per 1,000 (1 in 59) children 8 years of age (Baio et al., 2018). The 2016 National Survey of Children's Health (NSCH) estimated parent-reported ASD prevalence to be 1 in 40 (2.5%) children aged 3–17 years (Kogan et al., 2018). Variance in prevalence estimate systems could be partially due to regional and policy differences in the accessibility of evaluation and diagnostic services for children (Baio et al., 2018).
According to data from the CDC, ASD prevalence was significantly higher in boys (26.6 per 1,000) than in girls (6.6 per 1,000). The estimated ASD prevalence for White children (17.2 per 1,000) was 7% greater than that for Black children (16.0 per 1,000) and was 22% greater than the estimated rates for Hispanic children (14.0 per 1,000). The overall estimated ASD prevalence for Asian/Pacific Islander children was 13.5 per 1,000 (Baio et al., 2018).