Abstract

Introduction
Both Building Early Sentences Therapy (BEST) and the Derbyshire Language Scheme (DLS) are effective in improving children’s use and understanding of simple sentences. (1, 2). BEST is based on ‘usage-based’ linguistic theory. The underlying hypothesis being that by systematically manipulating the nature and quantity of the language a child hears, BEST can promote abstract, flexible knowledge and use of a range of sentence structures, and so accelerate future language learning (3). Comparisons of effective interventions enable practitioners, parents, and services to make informed choices regarding which work best for a given child, context, or family preference. Furthermore, comparing interventions delivered with the same dosage, delivery context, level of treatment fidelity and similar resources tests whether it is the specific learning mechanisms exploited by the interventions which promote change.

Aim(s)
to determine whether
• BEST and an adapted DLS (A-DLS) differ in efficacy,
• BEST and A-DLS differ in the degree to which benefits generalise to broader language and communication skills,
• BEST accelerates progress after intervention as predicted by usage-based theory.
Methods
Design: Twenty schools were independently randomised to receive BEST or A-DLS. Measures were collected at baseline, outcome (immediately post-intervention), and follow-up (~2 months post-intervention).
Participants: Consenting children aged 3;05–4;05, identified by teachers as monolingual English speakers, and not meeting age-related expectations in their language development, were assessed and included if they: Scored ≤ 16th centile on the New Reynell Developmental Language Scales (NRDLS) (4) comprehension and/or production subscales and had no reported sensorineural hearing impairment, severe visual impairment or diagnosed learning disability.
Interventions were delivered twice weekly in nurseries in groups for eight weeks by qualified Speech and Language Therapist researchers, trained to deliver the interventions with high fidelity. BEST and A-DLS were manualised and delivered with standardised resources and treatment fidelity was checked by members of the research team.
Measures were completed at baseline, outcome and follow-up, blind to intervention arm. Primary outcomes were the comprehension and production subscales of the NRDLS. Secondary outcomes measured targeted structures (BEST picture description, an adapted DLS rapid screening test and teacher reported functional communication (FOCUS: functional communication in Children under Six (5)).
Data analysis: ANOVAs comparing intervention groups on each outcome measure at outcome and follow-up adjusting for baseline differences where necessary.
Results and Conclusions
One-hundred-and-two children participated. Primary outcome: There were no differences in NRDLS comprehension or production standard scores at outcome but children receiving BEST had significantly higher comprehension and production standard scores at follow-up. Secondary outcomes: No significant differences. Both interventions were associated with large clinically meaningful changes on the FOCUS.