Randomized trial of a population-based, home-delivered intervention for preschool language delay

Population approaches to lessen the adverse impacts of preschool language delay remain elusive. We aimed to determine whether systematic ascertainment of language delay at age 4 years, followed by a 10-month, 1-on-1 intervention, improves language and related outcomes at age 5 years.

A randomized trial nested within a cross-sectional ascertainment of language delay. Children with expressive and/or receptive language scores more than 1.25 SD below the mean at age 4 years entered the trial. Children randomly allocated to the intervention received 18 1-hour home-based therapy sessions. The primary outcomes were receptive and expressive language (Clinical Evaluation of Language Fundamentals - Preschool, 2(nd) Edition) and secondary outcomes were child phonological skills, letter awareness, pragmatic skills, behavior, and quality of life.

A total of 1464 children were assessed for language delay at age 4 years. Of 266 eligible children, 200 (13.6%) entered the trial, with 91 intervention (92% of 99) and 88 control (87% of 101) children retained at age 5 years. At age 5 years, there was weak evidence of benefit to expressive (adjusted mean difference, intervention - control, 2.0; 95% confidence interval [CI] -0.5 to 4.4; P = .12) but not receptive (0.6; 95% CI -2.5 to 3.8; P = .69) language. The intervention improved phonological awareness skills (5.0; 95% CI 2.2 to 7.8; P < .001) and letter knowledge (2.4; 95% CI 0.3 to 4.5; P = .03), but not other secondary outcomes.

A standardized yet flexible 18-session language intervention was successfully delivered by non-specialist staff, found to be acceptable and feasible, and has the potential to improve long-term consequences of early language delay within a public health framework.