Treatment Adherence and Dose As Predictors of Child Language Outcomes in Pivotal Response Group Parent Training

Background: Behavioral interventions are robustly supported in ASD treatment, including those that are parent-administered. Previous research supports that group parent training in Pivotal Response Treatment (PRTG) results in gains in child language ability (Hardan et al., 2015). There remains a need, however, for better understanding of the relationship between parent fidelity of treatment implementation, dose of treatment, and child outcomes.

Objectives: To evaluate relationships between adherence to implementation, therapy dose, and child language outcomes from a randomized controlled trial of PRTG.

Methods: Participants included parents and their children, ages 2-6 years, with diagnoses of ASD and significant language delay. In the RCT, 53 participants were randomly assigned to either PRTG or a parent psychoeducation group (PEG). PRTG consisted of 12 weeks of parent training in the delivery of pivotal response therapy targeting language development. Parent adherence to PRTG implementation (defined as % fidelity to pre-defined therapy characteristics achieved) and dose (defined as the number of parent-implemented child learning opportunities) were coded at baseline, mid-point (week 6), and endpoint (week 12). The dependent measure was the number of child utterances at week 12 based on a structured laboratory observation. Linear regression and structural mediational models were used to evaluate relationships between PRTG treatment, parent fidelity, child learning opportunities, and child utterances.

Results: PRTG treatment substantially increased both fidelity and learning opportunities by week 6. At week 12, child learning opportunities was a significant independent predictor of child utterances, even after accounting for non-verbal ability. However, the relationship between parent fidelity and child learning opportunities was substantial (r=.66) and this shared variance was the biggest predictor of child utterances. Mediational models indicated that PRTG treatment resulted in early and ongoing improvements in parent fidelity, which lead to increases in the number of child learning opportunities, which, in turn, resulted in increased child utterances.

Conclusions: The present findings indicated the attention PRTG treatment provides leads to early and ongoing improvements in the quality of therapy provided by parents. These improvements in therapy quality coincide with improvements in the number of learning opportunities and together these enhancements in treatment adherence and dose improve child language outcomes. Results highlight the importance of therapy adherence and dose as crucial, consistent with findings from early intensive behavioral intervention studies. Parent-based behavioral intervention strategies should continue to emphasize treatment adherence throughout the delivery of treatment, as this is an important determinant of success via increasing the number of child learning opportunities. Additional research is needed to establish appropriate dosing of parent training to maximize child outcomes, but the present results suggest that 12 weeks is a useful lower bound.