Predicting Autism Spectrum Disorder from Combinations of Early Social Communication Skills Utilizing Decision-Learning Trees

Objective: There is substantial variability in early diagnostic features of autism spectrum disorder (ASD), suggesting heterogeneity in clinical presentation. The present study aims to identify distinct profiles of social communication skills that predict ASD. Method: The Communication and Symbolic Behavior Scales (CSBS) Behavior Sample was completed on 981 children at 16-24 months. All children also received a follow-up evaluation at 2-5 years. Two types of decision-learning trees, random forests (RF) and conditional classification and regression tree (CART), were used to analyze CSBS unweighted raw scores to predict diagnostic outcomes of ASD, developmental delay (DD), and typical development (TD). Results: RF results identified gaze shifts and gaze/point follow as the strongest predictors in differentiating diagnostic status. Six additional robust predictors were selected for inclusion in the conditional CART model. Nine profiles emerged and demonstrated an overall classification accuracy of 82.2%. The profile that predicted the largest proportion of children with ASD included low scores on the following CSBS items: gaze shifts, acts for joint attention, understanding, and distal gestures. Another subgroup of children with ASD demonstrated a typical number of gaze shifts, but deficits in gaze/point follow and initiation of joint attention. A third profile, highly predictive of TD, included developmentally appropriate scores on gaze shifts, gaze/point follow, rate of communication, and understanding. T-tests were conducted on children with ASD to examine characteristics of children accurately and inaccurately classified by the conditional CART model. Compared to children correctly classified, misclassified children demonstrated better social communication skills between 16-24 months, and higher verbal and nonverbal developmental levels, fewer restricted/repetitive behaviors, and comparable social communication autism symptoms between 2-5 years. Conclusion: Children diagnosed with ASD demonstrated nine different combinations of social communication skills between 16-24 months of age, suggesting heterogeneous behavioral presentations in the second year of life. Clinical implications and future research directions are discussed.