Who Benefits Most? A Randomized Controlled Trial for Parent-Implemented Social Communication Intervention for Chinese-Speaking Autistic Preschoolers

Background Parent-implemented interventions (PIIs) are well established for improving developmental outcomes in autistic children. As evidence for overall efficacy has accumulated, the field has increasingly shifted toward understanding for whom, and through which delivery formats PIIs are most effective. These questions are pressing in non-Western contexts, where access to professional services is limited, culturally appropriate interventions are needed. This RCT, one of the largest of its kind in China, addressed this gap by comparing two scalable delivery formats of a culturally adapted social communication program (speech-language therapist (SLT)-led online groups vs. flexible Self-study format) and examining differential intervention responses and sustained engagement.Methods A total of 112 Chinese-speaking autistic children aged 24–60 months with limited spontaneous expressive language were randomized to a 20-week SLT-led or Self-study intervention. Autism severity, social functioning, and communication skills were assessed at baseline, post-intervention, and 12 months after baseline. Parental stress, competence, and strategy use were also measured. Child, parent, and family characteristics predicting differential outcomes and engagement were examined. Results Both formats improved children’s expressive and receptive language and enhanced parental self-efficacy while reducing stress. Individualized analyses indicated greater benefits of the SLT-led format for children from lower-income families and those with greater developmental needs, whereas families with stronger baseline functioning showed comparable gains in the Self-study format. Attrition was higher in the Self-study format and was associated with lower child engagement and reduced parental capacity for independent implementation.Limitations The study was powered primarily to detect within-format effects, which may have limited sensitivity to identify subtle between-format differences. Parental strategy use was measured using a general interaction coding scheme rather than intervention-specific behaviors. Higher attrition in the Self-study format warrants cautious interpretation, although sensitivity analyses supported the robustness of findings.Conclusions: This study provides evidence for a culturally grounded PII that improves developmental outcomes in autistic preschoolers while enhancing parental self-efficacy and reducing stress. While both formats were effective, SLT-led support appeared particularly beneficial for families with greater needs, whereas the Self-study format was better suited to families with stronger baseline capacity, underscoring the importance of tailoring intervention formats to family characteristics.