Study designs of evaluations included in the review
For intervention: the studies had to detail the number of participants in each group and the nature, duration, span, and delivery of treatment, provide a comparison of pre- and post- intervention speech and language measures, and fulfill one of three design criteria: experimental study with randomised non-treatment controls; quasi-experimental studies (with non-random/pseudo-random or non-equivalent non-treatment control groups); or a single-subject experimental design with graphical displays or session-by-session data for individuals.
For screening tests: studies also had to included information on sample size, whether drawn from the general population, or a clinical population, or a mixed population, and had to give clear criteria for scores and report results expressed by both sensitivity and specificity.
Specific interventions included in the review
The authors state that approaches to interventions vary considerably. The interventions covered four broad areas: didactic (elicited imitation or mand modelling) approaches; naturalistic (interactionist or incidental teaching) approaches; hybrid (milieu therapy) approaches; and other approaches (non-directive therapy, auditory training, comprehension monitoring, and cognitive therapy). Specific categories used to identify the particular area of language investigated by the study were: attention control/concentration/listening skills, other prelinguistic skills, speech, expressive language, receptive language, general language, pragmatics/social use of language, cognitive abilities, and parent- child interaction. Screening interventions had to use tests designed for use in primary health care settings and/or in an educational setting by non-specialist staff for early identification, not diagnosis.
Reference standard test against which the new test was compared
The review did not include any diagnostic accuracy studies that compared the performance of the index test with a reference standard of diagnosis.
Participants included in the review
For effectiveness of intervention: children up to 7 years of age. For accuracy of screening: normal and clinical populations within the 0-7 year age range.
Studies had to be of primary speech and language delay. Studies focusing on ADD/ADHD; deafness/sensorineural loss; autism; psychiatric or EBD; Down's Syndrome; cerebral palsy; dyslexia; effects of social disadvantage; or other secondary speech and language delay were excluded.
Outcomes assessed in the review
Impact on speech/language delay. Main areas considered were articulation/phonology, expressive language, and auditory discrimination. A wide variety of scales appear to have been used to assess outcomes.
How were decisions on the relevance of primary studies made?
Final judgements about inclusion were made by two independent assessors, with discussion to resolve any disagreements.