Correspondence between the brief observation of symptoms of autism (BOSA) and the autism diagnostic observation schedule-2 (ADOS-2) in adolescents and adults

Autism research has historically focused primarily on children. Due to the introduction of the concept of a spectrum, changes to the autism diagnostic criteria, and a rise in awareness, there has been an increase of adults being referred for first-time autism assessment. Research has indicated differences in symptom profiles between adults diagnosed with autism in childhood and those diagnosed in adulthood; however, there are limited tools designed specifically to assess autism in adulthood. Concerns have arisen regarding higher rates of camouflaging in adulthood-diagnosed adults and how this may restrict clinicians’ ability to observe all autistic traits during comprehensive assessments, such as during the Autism Diagnostic Observation Schedule-2 (ADOS-2) when the patient is engaging with an unfamiliar person. The Brief Observation of Symptoms of Autism (BOSA), derived from the ADOS-2, was developed in response to in-person assessment restrictions during the COVID-19 pandemic. The BOSA focuses on interaction with a familiar other and has shown promise as an adapted tool. Due to the short duration and limited materials, the BOSA may be useful as a supplemental diagnostic measure for first-time diagnosis of adolescents or adults, or as a brief method to characterize participants in research studies. The present study sought to explore the utility of the BOSA and its correspondence to the ADOS-2 with a sample of forty-two adolescents and adults who completed the ADOS-2 and BOSA within the same visit. Results indicated that sensitivity and specificity of the ADOS-2 Modules 3 and 4 and BOSA F2 were comparable. The instruments yielded highly similar instrument classifications and behavioral item scores. Differences in some item scores highlight limitations of very brief observations and suggest potential areas for further refinement of the BOSA. Findings suggest the BOSA may provide an additional context in which to consider diagnostic features when assessing adolescents and adults and offers a feasible option for sample characterization in research.