School canteens are a recommended setting to influence adolescent dietary behaviours. Online canteens, whereby students can order and pay for their lunch online, are increasingly used by schools and represent attractive infrastructure to implement interventions that nudge users towards healthier food choices. A recent cluster RCT demonstrated the short-term effectiveness (2-month follow-up) of an intervention to increase the healthiness of foods purchased by high school students from online canteens. However, there is little evidence regarding the long-term effectiveness of interventions targeting adolescent food purchases, particularly those delivered online. This study aimed to assess the long-term effectiveness of a multi-strategy intervention embedded in online high school canteens at 15-month follow-up. A cluster RCT was undertaken with 1331 students (from 9 high schools) in New South Wales (NSW) Australia. Schools were randomized to receive the intervention (strategies including menu labelling, positioning, feedback and prompting) or the control (standard online ordering). Primary outcomes were the average proportion of ‘Everyday’, ‘Occasional’ and ‘Should not be sold’ items purchased per student (classified according to the NSW Healthy School Canteen Strategy). From baseline to 15-month follow-up, on average, students in the intervention group ordered significantly more ‘Everyday’ items (+11.5%,95% CI: 7.3 to 15.6, P<0.001), and significantly fewer ‘Occasional’ (-5.4%,95% CI: -9.4 to -1.5, P=0.007) and ‘Should not be sold’ items (-6.0%, 95% CI: -9.1 to -2.9, P<0.001), relative to controls. Given their longer-term effectiveness, choice architecture interventions delivered via online canteens may represent a promising option for policymakers to support healthy eating among high school students.
The longer-term effectiveness of ‘Click & Crunch’: An RCT of a web-based intervention to improve healthy eating from high school online canteens
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