Table 1. Determining autism spectrum disorder (ASD) surveillance status based on the Diagnostic and Statistical Manual of Mental Disorder–Fourth Edition–Text Revision (DSM-IV-TR).

Autistic disorder	Child had 1) six or more DSM-IV-TR symptoms coded, with at least a) two social symptoms, b) one communication symptom, and c) one behavioral symptom, and 2) evidence of developmental concern by three years of age.
ASD	Child had 1) two or more DSM-IV-TR symptoms coded, with at least a) one social symptom and b) one communication or behavioral symptom, and 2) at least one behavior that distinguishes children with ASD from children with other developmental delays or disorders (including an ASD diagnosis).a
Suspected ASD: high certainty the child has ASD (Classified as non-ASD)	Child met criteria for autistic disorder but did not have evidence of developmental concern by three years of age, or child met the first or second criteria for ASD, above, but not both; and the clinician reviewer noted his or her certainty the child had ASD as 4 or 5 on a 5-point Likert scale.
Suspected ASD: low certainty the child has ASD (Classified as non-ASD)	Child met criteria for autistic disorder but did not have evidence of developmental concern by three years of age, or child met the first or second criteria for ASD, above, but not both; and the clinician reviewer noted his or her certainty the child had ASD as 1, 2, or 3 on a 5-point Likert scale.
Disqualified ASD (Classified as non-ASD)	Child met surveillance status for autistic disorder or ASD, but clinician reviewer disqualified child upon first primary review or after consensus discussion with another reviewer (e.g., symptoms better accounted for by another disorder).
Not applicable (Classified as non-ASD)	Child did not meet surveillance status for autistic disorder, ASD, or Suspected ASD, or child had a documented diagnosis of CDD or Rett.

^aBehaviors that distinguish children with ASD from children with other developmental delays or disorders are considered “red flags” for ASD that would prompt further evaluation if reported by a parent or observed by a healthcare professional. These discriminators are necessary for the DSM-IV-TR case definition of ASD.