(PS11-D86) Factors Influencing Age of Diagnosis with Autism Spectrum Disorder: Implications for Equity in the Diagnostic Process

Early identification of Autism Spectrum Disorder (ASD) is associated with numerous positive outcomes, including increased social communication skills (Landa & Kalb, 2012). Factors that influence age of ASD diagnosis may include geographic location and socioeconomic status (Mandell, 2005). More recently, the effect of diagnostic overshadowing has been considered, namely that the presence of other, co-occurring conditions may delay an ASD diagnosis (Miodovnik et al., 2015). To date, no study has examined the combined influence of many co-occurring conditions in the context of environmental and demographic variables to determine which factors capture unique variance in the age of ASD diagnosis. The current study examined the influence of system-level, parent demographic, and child demographic factors on parent-reported age of ASD diagnosis in a sample of 304 children, aged 6-17 (M = 11.6, SD = 3.7).

The average age of ASD diagnosis was 5.5 years old. A multiple linear regression revealed an earlier age of ASD diagnosis for children from higher socioeconomic backgrounds (β = -5.99, SE = 2.54, p = .018), as well as those who received more developmental services (β = -16.37, p < .001), or who had a co-occurring intellectual disability (ID; β = -11.93, SE = 5.20, p = .022). A later age of ASD diagnosis was found for children living in the Midwest of the United States (β = 18.50, SE = 6.83, p = .007) as well as for children with co-occurring diagnoses of anxiety (β = 11.08, SE = 4.06, p = .006), a mood disorder (β = 12.56, SE = 5.40 p = .020), or Disruptive Mood Dysregulation Disorder (DMDD; β = 29.93, SE = 9.60, p = .002).

The average age of ASD diagnosis obtained in the sample is over three years later than when autism can be reliably diagnosed (Lord et al., 2006). This discrepancy is a matter of social justice because access to services and receipt of their benefits are contingent on early identification. Findings replicate geographic trends in age of diagnosis, namely that youth in the Midwest are diagnosed, on average, 18 months later than youth in the Northeast. This disparity is likely reflective of differential access to health care in these regions (Adelman & Kubiszyn, 2017). Additionally, families with higher socioeconomic status may have greater resources to obtain an earlier diagnosis of ASD (Daniels & Mandell, 2013). Similarly, receiving more developmental services provides oversight from multiple professionals which may facilitate earlier identification. A co-occurring ID may also contribute to receiving a timelier diagnosis (Leader et al., 2022). Finally, diagnostic overshadowing was noted via diagnosis of ASD occurring later, on average, in the presence of co-occurring anxiety (11 months delay), mood disorders (13 months delay), or DMDD (30 months delay). Practitioners may have difficulty identifying ASD when symptoms of these other diagnoses are present (Mazefsky et al., 2012). Findings replicate literature highlighting the importance of addressing service disparities by geographic region and socioeconomic status. The novel contribution of several mood and anxiety disorders in delaying ASD diagnosis suggests the need for additional provider training in identifying and conceptualizing ASD in the context of anxiety and mood symptoms.