Positive behavioural support for children and young people with developmental disabilities in special education settings: A systematic review.

Twenty-nine of the thirty studies were single-case designs and one was a pre-post group study with no control group. No randomised controlled trials were identified, so causal conclusions about PBS effectiveness cannot be drawn. Blinding of participants, personnel and outcome assessors was either not reported or rated unsure in every study, and procedural fidelity was high risk of bias in half the studies. This means observer effects cannot be ruled out. Only two studies formally assessed quality of life despite it being a stated primary goal of the framework, so the review cannot speak to whether PBS improves wellbeing beyond reducing challenging behaviour. No studies reported data on facilitators or barriers to implementation, so the review offers nothing on how to make PBS work in practice. Outcome measures varied widely across studies, preventing meta-analysis and making it impossible to compare effect sizes or determine which components matter most. Ninety percent of included studies were conducted in the USA and all were published in English, limiting generalisability to other education systems. Many studies did not explicitly label their approach as PBS. The authors identified eligible studies by matching them against a predefined framework, which may have introduced selection bias.

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Do not read the high proportion of studies reporting reductions in challenging behaviour as evidence that PBS works. Twenty-nine of the thirty studies were single-case designs with no control group, blinding was absent or unreported in every study, and procedural fidelity was high risk of bias in half. These studies show that behaviour changed during the intervention, not that the intervention caused the change.