Standardized Measures of Improvement in Language Across Two Randomized Clinical Trials of Pivotal Response Treatment

Background: Pivotal Response Treatment (PRT) is an evidence-based naturalistic behavioral intervention. Support for its use in improving language abilities has historically come from single-case studies using primarily behavioral observation measures. There is a critical need for examination of outcomes from larger samples and from objective measures which can be more easily compared across trials and to normative developmental trajectories.

Objectives:  This presentation will review standardized language outcomes from two randomized controlled trials of PRT, including a 12-week trial of PRT Group treatment (PRTG) and a 24-week PRT package treatment (PRT-P) which combines parent training with clinician-delivered in-home treatment. Our aim is to highlight new data demonstrating how standardized measures of language and cognitive abilities can be used to assess treatment response in clinical trials.

Methods:  Participants include children with ASD and significant language delay, ages 2-6 years. Participants in the first trial were randomly assigned to either PRTG or a parent psychoeducation control group. Participants in the second trial were randomly assigned to either PRT-P or delayed treatment.  Dependent measures include objective tests of language and cognitive abilities as well as Clinical Global Impression Improvement (CGI-I) ratings by raters blinded to treatment condition and standardized parent questionnaires.

Results: The PRTG trial has been completed and the PRT-P trial is ongoing; data are currently available from 47 participants from PRTG and 28 from PRT-P. Findings from the PRTG trial revealed significant improvement on Vineland Adaptive Behavior Scales Communication Scale in the active group compared to control (F(2,19) = 3.80, p = .041). CGI-I ratings focusing on communication also indicated greater improvement in the PRTG compared to controls (F(1, 44) = 15.97, p < .001). A non-significant trend was observed for MacArthur-Bates Communicative Development Inventories (CDI) mean length of longest utterance (F(2, 32) = 3.09, p = .059). Three-month follow-up data revealed that children maintained their improvement on the Vineland Communication Domain Standard Score (F(2, 12):11.74, p=.001) and cognitive improvement was observed on the Mullen Scales of Early Learning Composite score (F(1, 20)= 5.43, p=.03). Similarly, preliminary findings from the PRT-P trial revealed children in the active group are acquiring greater vocabulary as evidenced by an average gain of over 150 words on the CDI between baseline (M=126.6 ± 111.2) and post treatment (M=281.0 ± 194.3), which was significantly greater than changes observed in the control (F(1,20)=5.267, p=0.037). CGI-I ratings indicate that the PRT-P group is showing more overall improvement compared to controls (X²= 9.363; p=0.025).  Finally, we present data from using the Language ENvironment Analysis (LENA) system to assess generalized language improvements from automated analysis of natural environment audio recordings.

Conclusions:  These data provide support for the application of PRT to improve child language and cognitive abilities. At the same time, comparison of standardized language measures across trials reveals clear differences in outcomes which may be attributed to differences in treatment delivery models and to sample characteristics. We will discuss these differences by highlighting the advantages and challenges of specific standardized measures, and provide recommendations for the design of future trials.