Evaluating a targeted selective speech, language, and communication intervention at scale - Protocol for the Happy Talk cluster randomised controlled trial.

Background: In areas of social disadvantage up to 40-50% of children enter preschool with speech and language skills significantly poorer than would be expected for their age. The Happy Talk trial tests if a community embedded, targeted selective speech and language programme that simultaneously engages with parents and early childhood educators, (1) improves language outcomes in children aged between 2 years 10 months and 6 years and (2) is cost effective for the health care system.

Method: The Happy Talk trial is a large scale cluster randomised trial of a 12-week manualised intervention delivered in pre/school settings serving socially disadvantaged communities, in Ireland. Seventy-two clusters will receive the intervention (12 participants per cluster). Parents and pre/school staff engage in group training and coaching in the form of 12 1-hour sessions for parents and four staff workshops, over the course of the pre/school year. Training/coaching includes core interaction skills (modelling, expanding, balancing questions and comments), early literacy and phonological awareness. Blinded assessments pre- and immediately post-intervention and at 6 months follow up, will measure the primary outcomes of children's receptive and expressive language and functional impact, and secondary outcomes of quality of life. Parental responsiveness and educator-child interactions will also be evaluated.

Discussion: This robust study evaluates a public health approach to the delivery of speech language and communication intervention in the 'real world' in the community, which focuses on prevention and equity of access. Pilot work indicates that the programme is feasible, acceptable to parents and staff, cost effective, and suitable for implementation at scale. The trial includes a process evaluation, a well-developed economic evaluation and the outcomes are directly relevant to children, families and educators. This work has the potential to improve the long-term outcomes and life chances of people living in social disadvantage.

Trial registration: clinicaltrials.gov NCT06460090.

Trial management: There is a formal governance structure to oversee the conduct and running of the trial, consisting of a trial management group and a steering committee. More details on the composition, roles and responsibilities of each committee can be found in the supplemental material.