Predicting Differences in Age of ASD Diagnosis within a Multi-Stage Screening Protocol

Background: Early detection of ASD is thought to promote better long-term outcomes, by enabling earlier uptake of ASD intervention; however, a roughly 1.5-year gap persists between the age at which ASD can typically be diagnosed (< age 2) and the national median diagnostic age (3 years, 10 months; Baio et al., 2014). Moreover, children of racial or ethnic minorities are diagnosed significantly later than White children (Mandell et al., 2009).

Objectives: The aim of the present study is to determine factors that distinguish children who receive an ASD diagnosis before 2 years of age from those who receive a later diagnosis.

Methods: This study occurs within the context of a multi-stage screening and assessment protocol aimed at decreasing disparities in ASD diagnosis and service receipt. The project partners with local Early Intervention (EI) agencies to identify children at risk for ASD by disseminating a two stage screening process. Partnering EI agencies administer Stage 1 parent-reported questionnaires of child functioning. Children who obtain scores above cut-offs or have a parent or EI provider express concern regarding ASD, were referred to Stage 2, a play-based observational assessment. Children who screened positive at Stage 2 were referred to a research-based diagnostic evaluation prior to 36-months of age, when children transition out of EI services.

The majority of the 395 (16.2% female) participants received a diagnosis between the age of 2 and 3 (mean: 28 months, range: 16-38 months). Participants were divided into three age groups: 14-23 months; 24-30 months; and 31-36 months at ASD diagnosis. The sample was diverse with respect to race/ethnicity (76 White non-Hispanic, 98 Black, 224 Latinx, and 25 Asian participants), immigration status (53.7%), English learner status (35.8%), and poverty status (58.7%). Performance on screening measures, level of parental concern, and family demographic factors were compared among age groups.

Results: Children diagnosed under 24 months were more likely to be White non-Hispanic than Black, Latinx, or Asian, x²(6)=17.27, p=.008. However, groups did not differ by English language learner status, immigration status, household income, or parental education. A series of one-way ANOVAs indicated that diagnostic-age groups did not differ in Stage 1 scores of ASD-specific problems or competencies, nor did they differ in the presence of parental concerns about a) ASD, b) child language, or c) child behavior, emotions, and relationships.

Conclusions: Because the current study took place within the context of a screening protocol that is specifically designed to address and reduce health disparities in rates and age of diagnosis, we expected to see no differences in age of diagnosis. The fact that only race, but not other known social determinants of health such as income, English learner status, or parent education, related to diagnostic age, suggests that racial discrimination, race-related systemic factors, and/or ethnically and culturally-relevant barriers may be at play. Next steps include incorporating Department of Public Health data on EI referral reason and age of entry to further understand the sources of these age-related disparities.