Background and Aims Moving a child from booster seat to adult lap and sash belt too soon is common in Australia and worldwide. This can increase the severity of injury in the event of trauma in a motor vehicle crash. While there is an existing tool (the 5-step test) to support parents in making the transition decision, to our knowledge, this tool has never been studied for effectiveness. The aim of this study was to identify strengths and weaknesses of the 5-step test.

Methods A randomised controlled design was used to determine differences in the decision-making processes that parents engage when transitioning out of a booster using the existing 5-step test (intervention group) compared to the legal requirements (control group). Using a purpose-built rig, belt fit conditions were adjusted based on child’s anthropomorphic measurements. Parents of children aged 7–12 years were then asked to ‘think out loud’ as they assessed the appropriateness of an adult seatbelt when observing their child in three different seatbelt fit conditions (good, poor, and partially good fit).

Results and Conclusion Preliminary results show parents using the 5-step test made more accurate decisions about the appropriateness of their child using the adult seatbelt compared to control group, but there are clear opportunities to improve and refine the tool to better support parents making this transition decision. Future studies should include input from parents and carers whist mapping behaviour markers using Behaviour Change Techniques when creating improved resources to support parents making transition decisions.