BACKGROUND: In recent years there has been a significant increase in the number and quality of childhood apraxia of speech (CAS) treatment research published. Much of this research has focussed on establishing treatment efficacy and identifying treatment components. A smaller subset of the literature has looked at treatment intensity, such as comparing therapy delivered twice per week with four times per week, however this literature has not been compared across interventions. AIMS: This systematic review and meta-analysis examines cumulative intervention intensity and its components (dose per session, dose frequency, intervention duration-number of weeks) and reported treatment effects to understand whether there is a relationship between dose and effect in specific treatments or overall. METHODS: A systematic search and review was registered with Prospero (CRD420251107259). Twelve electronic databases were searched supplemented by handsearching references lists. Included studies were coded for CAS diagnosis confidence, methodological quality, dose characteristics, and treatment outcomes. Standard mean difference (SMD), an effect size metric equivalent to Cohen's d, was calculated for 25 included papers and weighted Pearson's correlations performed to identify relationships between dose characteristics and treatment outcomes. MAIN CONTRIBUTION: This paper is the first to (1) create omnibus standard effect sizes across diverse interventions and (2) show the relationship between intensity and treatment outcome in children with CAS. The omnibus SMD across studies with three or more participants for treated items was 1.22 (confidence interval 0.76-1.67), a large effect, and for generalisation items was 0.66 (confidence interval 0.46-0.85) which is a moderate effect. These results show that CAS treatment works in well-controlled studies when delivered at least twice per week for at least 45 min per session. The relationship between intensity variables and generalisation SMD was less clear with weeks of therapy being moderately correlated (r = 0.39) and none of the other variables showing any relationship with study SMD. These results should be interpreted carefully as there was significant missing data and limited range in some variables. Researchers need to include more standard intensity information in reporting their results. CONCLUSIONS: Treatment for CAS is effective and leads to moderate generalisation; more weeks of therapy leads to stronger gains than fewer weeks of therapy. WHAT THIS PAPER ADDS: What is already known on this subject CAS is a neurological-based motor speech disorder that originates in childhood for which there are a number of effective treatments. For this population, high intensity treatment is recommended-over 100 production trials per session, 2-5 sessions per week, across an extended period. In studies which directly compare intensity of variables, more therapy (e.g. 20 sessions) results in greater improvement than less therapy (e.g. 10 sessions). There are no previous meta-analyses of intensity variables-dose, dose frequency, treatment duration, or cumulative intervention intensity in CAS What this study adds to the existing knowledge This study compiles data from 25 studies with a low risk of bias and high CAS diagnostic confidence in a meta-analysis of the dose effects of CAS treatment. The meta-analysis shows that CAS treatment in general works. Most studies had 2-4 sessions per week across 3-12 weeks. Within this narrow band of intensity, a significant correlation was shown between the number of weeks of therapy and outcome. There is no significant evidence for CAS therapy less frequently than twice per week at this time. Eight different treatments demonstrated efficacy for improving speech outcomes in children with CAS. What are the clinical implications of this study? Provided they are delivered at least twice per week for at least 12 sessions, with greater improvements when treatment extends over more weeks, selection of any of the included treatments should result in improved speech where the child being treated is similar to children in the research. The following treatments were shown to be effective for CAS: Integral stimulation treatments including Dynamic Temporal and Tactile Cueing, Kaufman-Speech to Language Protocol, Motor Speech Treatment Protocol, Nuffield Dyspraxia Programme-3rd Edition, Rapid Syllable Transition Treatment, Speech Motor Chaining and Ultrasound Biofeedback alone and the combination of Speech Motor Chaining with Ultrasound Biofeedback. PRACTITIONER POINTS: Therapy must be sufficiently frequent and sustained: Evidence shows that CAS treatment is effective when therapy is provided at least twice per week, over a minimum of 12 sessions, for 45 min per session with total weeks of therapy being the only intensity variable consistently associated with treatment outcomes. Dose matters, both within and across sessions: Clinicians should prioritise the number of production trials and ensure adequate cumulative intervention intensity. Sessions with low active practice time or insufficient trials are unlikely to produce meaningful change. Eight treatments are effective for CAS: Integral Stimulation including Dynamic Temporal and Tactile Cueing (DTTC), Kaufman Speech to Language Program (K-SLP), Motor Speech Treatment Protocol (MSTP), Nuffield Dyspraxia Programme (3rd ed; NDP3), Rapid Syllable Transition Treatment (ReST), Speech Motor Chaining (SMC), Ultrasound Biofeedback, and SMC + Ultrasound Biofeedback combined. Clinicians should consider the client's speech needs and overall profile when selecting from the treatments that have demonstrated effectiveness.
