Screening for autism in toddlers: a follow-up study

The present study follows children who were originally screened for an Autism Spectrum Disorder (ASD) as toddlers through a large community-based pediatric practice. We evaluated the children after their 3rd birthday to examine their diagnostic course and clinical presentation. Of the 796 families screened at Time 1, 51 families were eligible for an in-person screening based on questionnaire results; 30 chose to participate. All 51 families were recontacted and asked to participate in a follow-up evaluation (Time 2). Twenty-four families participated in a 3-hour diagnostic assessment including cognitive and adaptive testing and parent interviews. Overall accuracy (Positive Predictive Values; PPV) of the study was calculated and group cognitive and adaptive profiles were examined. The PPV for the screening process as a whole was 0.90 for ASD (9 of 10 children were correctly identified as Early Autism; EAD). PPV from questionnaire scores alone (i.e., positive screen scores on either the Modified Checklist for Autism and Toddlers; M-CHAT or Infant Toddler Checklist; ITC) would have been 0.06 (9/145), and PPV from the phone-follow-up would have been 0.43 (9/24). The ASD group demonstrated lower scores on the nonverbal domains of the Mullen Scales of Early Learning and on the Socialization domain of the Vineland Adaptive Behavior Scales. Our results suggest that a systematic screening process in a large, community-based pediatric practice accurately identified toddlers who would go on to meet Diagnostic and Statistical Manual of Mental Disorders - Fourth Edition (DSM-IV) criteria for Autistic Disorder or Pervasive Developmental Disorder - Not Otherwise Specified (PDDNOS) after the age of 3 years, without over-identifying children or providing a significant number of unnecessary evaluations. Larger systematic screening studies are needed to further examine general population samples for ASD.