Scaling Up Caregiver Support for Autism in Public Health Care: Adoption, Implementation Pace and Sustainability of a Train-the-Trainer Model for the WHO Caregiver Skills Training in Italy

Train-the-Trainer (TTT) models can scale parent-mediated interventions (PMIs) in public health care, yet evidence on large-scale implementation remains limited. This study reports the implementation of an adapted TTT model for the WHO Caregiver Skills Training (CST) within the Italian National Health Service, evaluating adoption, acceptability, feasibility and sustainability. Twenty-eight clinicians from 10 Regions undertook the four-phase TTT. A mixed-methods design combined surveys with focus groups, analyzed using the Consolidated Framework for Implementation Research (CFIR). Twenty trainees (71%) qualified as Master Trainers (MTs), and 17 of these (85%) trained facilitators; 60% of MTs achieved full fidelity within the expected timeline. Satisfaction ratings were high, whereas feasibility ratings were mid-range. Implementation inhibitors clustered in the CFIR Inner setting (available resources, leadership engagement), Outer setting (lack of formal recognition), and Process (training model's intensity structure) domains. Accelerators included Characteristics of individuals (motivation, readiness to change), Intervention characteristics (responsiveness to families' needs, accessibility) and Inner Setting features (integration within existing care pathways). Overall, the adapted TTT was acceptable and supported early adoption and fidelity; however, lower feasibility for select capacity-building components and multilevel barriers indicate that sustained integration will require stronger organizational support and policy endorsement. Proposed adaptations offer an adaptable framework for global efforts to expand caregiver support within public health systems.Lay AbstractFamilies of autistic children often benefit from programs that teach caregivers practical skills to support their child's development. However, these programs can be hard to implement in public health systems due to a shortage of trained professionals and because interventions may not align with existing service structures. To overcome these challenges, the Italian National Institute of Health has implemented the World Health Organization's Caregiver Skills Training (CST) program through initiatives funded by the National Autism Fund. To ensure the program could be effectively adopted within the Italian public health context, we applied a "Train-the-Trainer" model. This approach trains experienced clinicians to become "Master Trainers," who in turn train other professionals to deliver the program to families, supporting scalability and sustainability within the system. In our study, 28 clinicians from 10 regions of Italy took part in a four-step training process. Most (20 trainees) completed the program successfully, and many (17 trainees) went on to train facilitators. Surveys and focus groups examined how well the program was taken up, how acceptable it felt, how doable it was in routine services, and what might help it last. Trainers reported high satisfaction with the program, although some faced difficulties such as limited institutional support. Factors that helped implementation included strong motivation and the program's perceived usefulness for families. Barriers included organizational challenges and the need for formal recognition of the program. Overall, this approach looks promising for bringing CST into public services, but durable, wider use will require stronger organizational support and policy endorsement. The proposed adjustments offer a practical path to expand caregiver support and offer methods that can be transferred to public health systems in other countries.