Accuracy of initial diagnostic impressions of autism in toddlers and behaviors that inform these impressions.

Clinicians form initial impressions about a child's diagnosis based on behavioral features, but research has not yet identified specific behaviors to guide initial diagnostic impressions. Participants were toddlers (N = 55, mean age 22.9 months) from a multi-site early detection study, referred for concern for ASD due to screening or parent/provider concern. Within 5 min of meeting a child, clinicians noted ASD or non-ASD impression, confidence in impression, and behaviors that informed their impression. These clinicians also determined final diagnoses for each child. When a child's final diagnosis was ASD (n = 35), senior clinicians formed an initial impression of ASD in 22 cases (63%) but missed 13 cases (37%). When final diagnosis was non-ASD (n = 20), senior clinicians made an initial impression of non-ASD in all cases (100%). Results were similar among junior clinicians. Senior and junior clinicians used the same behaviors to form accurate impressions of ASD and non-ASD: social reciprocity, nonverbal communication, and eye contact. Senior clinicians additionally used focus of attention when forming accurate impressions of ASD and non-ASD; junior clinicians used this behavior only when forming accurate non-ASD impressions. Clinicians' initial impressions of ASD are very likely to be consistent with final diagnoses, but initial impressions of non-ASD need follow-up. Toddlers who show all four atypical behaviors (social reciprocity, nonverbal communication, eye contact, and focus of attention) might receive expedited ASD diagnoses. However, presence of apparently typical behaviors should not rule out ASD; for some children a longer evaluation is necessary to allow for more opportunities to observe subtle social behavior.