Trial protocol: A hybrid effectiveness-implementation study of Paediatric Autism Communication Therapy (PACT) in the Brazilian public health system

In Brazil, autistic children and their families face significant challenges in accessing evidence-based interventions, especially via the national public health service. Here, we report the protocol for a hybrid effectiveness-implementation trial, which will investigate the large-scale implementation of Paediatric Autism Communication Therapy (PACT) as well as its real-world effectiveness in Brazilian public health services for autistic children. Eligible professionals from public health services across the five regions of Brazil will be trained in PACT. They will deliver the intervention, which consists of 14 sessions delivered over 6 months, to dyads of autistic children and their caregivers in their regular clinical practice for the trial period of 18 months. We will use elements of three implementation science frameworks to systematically study factors that influence the implementation of PACT in this setting. To study effectiveness dyads will be randomised to receive PACT immediately or following a 6-month waitlist, stratified by healthcare service. Effectiveness outcomes (parent-child interaction, child adaptive social communication skills, caregiver well-being) will be collected pre- and post-PACT/waitlist and compared between groups. This trial will provide the first evidence on the effectiveness of PACT implemented in a public health system and the barriers and facilitators to such large-scale implementation.