Objectives: We examined the factor structure of the HSQ, modified for use with children with PDDs by the Research Units on Pediatric Psychopharmacology (RUPP) Autism Network. We also assessed its correspondence with indices of disruptive behavior (which would be suggestive of convergent validity) and adaptive behavior (suggestive of divergent validity).
Methods: Investigators from the RUPP Autism Network modified the HSQ by adding 5 situations where many children with PDDs have particular difficulty (for e.g., making transitions from one setting to another). This modified scale (HSQ-PDD) was used as the outcome measure in a clinical trial evaluating improvements in compliance as a function of pharmacological and behavioral treatment. In the current study, we analyzed HSQ-PDD data for the 124 subjects who participated in this 24-week, three-site RUPP clinical trial. Key inclusion criteria for the trial were presence of PDDs, and serious behavior problems as indicated by high scores on the Irritability subscale of the Aberrant Behavior Checklist (ABC).
Results: Exploratory factor analyses with oblique Crawford-Ferguson (CF) quartimax rotations were used to derive two-to-five factor solutions. The number of factors retained was based on information gained from eigen values, scree plots, measures of model fit, and clinical content. The 2-factor solution appeared to be the most parsimonious and interpretable. Factor 1 (n = 14 items) consisted of situations characterized by “Socially-Inflexible” behaviors. These included social situations where the child’s lack of adaptability becomes most prominent, such as deviation from an expected schedule, or adjusting to people or places outside the child’s immediate comfort zone. Factor 2 (n = 6 items), which we named “Demand-Specific”, consisted of situations where a direct demand was placed on the child and required effort. Item content of both subscales appeared to fit well with the rubric of PDDs. Internal consistency, using Cronbach’s alpha, was 0.90 for “Socially-Inflexible”, and 0.80 for “Demand-Specific.” These derived subscales showed moderate correlations with subscales of the ABC, Child and Adolescent Symptom Inventory, and Children’s Yale-Brown Obsessive Compulsive Scale, and low negative correlations with the Vineland Adaptive Behavior subscales.
Conclusions: The HSQ-PDD appears to be well suited for children with PDDs, and use of its two subscales will likely result in more refined interpretation of ratings than the more global total score. However, since participants were selected for the presence of behavior problems, it may not be appropriate to generalize results to all children with PDDs. Additional data from a broader range of children with PDDs would be helpful for confirming subscale content and developing norms.