Sex differences in the age of childhood autism diagnosis and the impact of co-occurring conditions.

This study looked at when boys and girls get diagnosed with autism and found important differences. Girls tend to get diagnosed either very early (before age 3) or much later (after age 11), while boys usually get diagnosed between ages 3-11. The researchers found that girls were more likely to have anxiety and mood problems before their autism diagnosis, which seemed to delay their autism diagnosis. When they accounted for these other conditions, the differences between boys and girls largely disappeared, suggesting these mental health conditions affect when autism gets diagnosed.

This retrospective cohort study analyzed electronic health records from 1,438 individuals (1,142 boys, 296 girls) diagnosed with autism at Duke University Health System between 2014-2021. The research examined sex differences in autism diagnosis age and the role of co-occurring conditions. Results showed girls were more likely to be diagnosed either very early (before age 3) or later (after age 11), while boys were typically diagnosed between ages 3-11. Girls had more anxiety and mood disorder visits prior to autism diagnosis, which were associated with later diagnosis.

Boys had more otolaryngology visits, associated with earlier diagnosis. When controlling for co-occurring conditions, sex differences in diagnosis age became non-significant, suggesting these conditions mediate the relationship between sex and diagnosis timing.

Clinicians should maintain awareness of autism possibility in girls presenting with anxiety or mood symptoms, particularly after age 11. Early intervention services should consider sex-specific patterns in diagnosis timing. Healthcare systems may benefit from developing screening protocols that account for different presentation patterns between boys and girls.

Single-center study from one academic medical center may limit generalizability. Retrospective design using electronic health records may miss relevant clinical information not documented in records. Study does not establish causality between co-occurring conditions and diagnosis timing.

Sex differences in the age of autism diagnosis during childhood have been documented consistently but remain poorly understood. In this study, we used electronic health records data from a diverse, academic medical center to quantify differences in the age of autism diagnosis between boys and girls and identify associations between the age of diagnosis and co-occurring neurodevelopmental, psychiatric, and medical conditions. An established computable phenotype was used to identify all autism diagnoses within the Duke University Health System between 2014 and 2021. Co-occurring neurodevelopmental and psychiatric diagnoses as well as visits to specific medical and supportive services were identified in the 2 years prior to the autism diagnosis.

Cox proportional hazards models were fitted to quantify associations between diagnosis age and sex with and without controlling for the presence of each co-occurring diagnosis and visit type. Records from 1438 individuals (1142 boys and 296 girls) were included. Girls were more likely to be diagnosed either before age 3 ( = 497.720, p < 0.001) or after age 11 ( = 4.014, p = 0.047), whereas boys were more likely to be diagnosed between ages 3 and 11 ( = 5.532, p = 0.019). Visits for anxiety ( = 4.200, p = 0.040) and mood disorders ( = 7.033, p = 0.008) were more common in girls and associated with later autism diagnosis (HR = 0.615, p < 0.001; and HR = 0.493, p < 0.001).

Visits for otolaryngology were more common in boys and associated with an earlier autism diagnosis (HR = 1.691, p < 0.001). After controlling for these conditions, associations between sex and diagnosis age were reduced and not statistically significant. These results show that the age of autism diagnosis differs in girls compared to boys, but these differences were neutralized when controlling for co-occurring neurodevelopmental and psychiatric conditions prior to autism diagnosis. Understanding sex differences and the possible mediating role of other diagnoses may suggest targets for intervention to promote earlier and more equitable diagnosis.