Mike: Hello, I'm Mike Clarke, podcast editor for the Cochrane Library. Before its closure in 2023, the Cochrane Injuries Group worked on more than 150 reviews and one of these, on interventions to encourage the use of seat belts was published in January 2024. Here's the lead author, Andrit Lourens from the Namibia University of Science and Technology to tell us about the findings.

Andrit: Each year, many people die or are seriously injured because of road traffic injuries. Seat belts are designed to protect the occupants of a vehicle but, despite laws that require seat belt use in many parts of the world, many people still don't use them, and we wanted to find out if there is evidence on ways to change this and found some promising results.
We investigated the effects of education, incentive or engineering-based interventions, but not law enforcement, to encourage seat belt use and determine which interventions are most effective. Educational-based interventions are structured programmes teaching drivers and passengers the importance of using seat belts. While incentives include rewards schemes and engineering-based interventions are design changes to the vehicle structure that promote the wearing of seat belts, such as seat belt alarms.
We searched for studies that allocated people travelling in commercial vehicles to interventions intended to improve seat belt use. We were looking for robust research designs and chose to include only randomised trials that evaluated education, engineering and/or incentive-based interventions. We wanted to look at the impact on the frequency of wearing a seat belt, as well as crash-related injuries and deaths, but none of the included studies reported on the latter health outcomes.
We found 15 eligible trials enrolling just over 12,000 participants, as well as four ongoing studies in our extensive searches in 2022. Thirteen of these trials – so a large majority - were conducted in the USA, with the other two conducted in Denmark and Russia; meaning that none were from low or middle-income countries where a large proportion of traffic-related injuries and deaths occur.
Twelve of the 15 studies looked at educational interventions alone, one at education and incentives (in one of the trial arms), and two at engineering-based interventions. All included studies reported on the frequency of wearing a seat belt, but all but three of them relied on participant self-reporting for this outcome. Two of these reported the frequency of wearing a seat belt through in-vehicle data monitoring systems and the other trial used observation.
There was some evidence suggesting that education and engineering-based interventions may promote seat belt use. Our confidence in the evidence was low or moderate, mainly due to the outcome, the wearing of seat belts, being measured through participant self-reporting. Self-reported outcomes are open to being influenced by participants answering in a manner they believe to be desirable or by participants' limited recollection of the event being studied.
Our overall conclusion is that there is an ongoing need for research to better understand the effectiveness of education- and engineering-based interventions on seat belt use, and to investigate the benefit of incentives, alone or combined with other interventions. There also needs to be research into other types of interventions, different combinations of interventions and different settings. Our review was limited by the small number of studies that met our design criteria, namely randomised trials, which are currently not very common in research into road user behaviour. Therefore, another of our recommendations is that more attention is given in future to research design in this area so that the efficacy of interventions can be assessed more rigorously.

Mike: If you'd like to read about the current evidence base, and watch for updates of this review if those new studies are done and the ongoing studies are completed, its available at Cochrane Library dot com. If you go to the website and simply search for 'seat belts', you'll find it.