Prior Diagnoses and Age of Diagnosis in Children Later Diagnosed with Autism.

Awareness of autism is rising, yet social determinants of health impact ages of diagnosis, and diagnostic load. Unequal rates of diagnoses may indicate biases in the healthcare system. This study investigates six prior diagnoses (ADHD, conduct, adjustment, anxiety, mood, and intellectual disability) assigned to children who are later diagnosed with autism. The study investigates how race, sex, and geographic factors were associated with age of diagnosis and diagnostic load. A sample of 13,850 (78.16% male and 14.43% Black, with 57.95% of children living in urban regions) children aged 2-10 who were diagnosed with autism on Missouri Medicaid between 2015 and 2019 were studied. Indicated that being White, living urban, and having more prior diagnoses were associated with older age of autism diagnosis. Using logistic regressions, being White was associated with a child being more likely diagnosed with all prior diagnoses aside from intellectual disability. Being male was related to a higher likelihood of ADHD, and lower likelihood of intellectual disability. Being White was associated with higher likelihood of most diagnoses, even in urban-only samples, potentially reflecting more access to providers and office visits. Living in rural areas was also associated with earlier diagnosis and more prior diagnoses such as ADHD and conduct, which may be due to types of providers or specialists seen. Future research should look at barriers to diagnosis and the advantages and disadvantages of a higher diagnostic load.