A single-blinded randomised controlled trial incentivising adults to increase public transport for health gain: The trips4health study

Incentives-based strategies can improve health behaviour. Public transport use confers individual- and societal-level public health gain but incentivising public transport has been under-explored. The study objective was to assess the effectiveness of financially incentivising public transport use from a public health perspective. trips4health was a single-blinded parallel group randomised controlled trial (RCT) conducted in Hobart, Australia. Participants were 18 + years and infrequent (<3 times/week) bus users who completed surveys and attended study clinics at baseline and post-intervention. Intervention group participants were set weekly bus use targets increasing over 16-weeks. Smartcard credit was awarded if targets were attained. Weekly text messages and educational materials supported incentives. An active control group received educational materials. 110 participants had been randomised to the control (n = 55) or intervention (n = 55) group when the trial was abandoned due to the COVID-19 pandemic; 65 % (n = 71; 34 intervention, 38 control) completed a 16-week intervention period. The percentage of participants using the bus during the 16-week intervention period was higher in the intervention (69 %) than the control (49 %) group, target attainment (intervention) or their equivalent (control) was higher in the intervention (22 %) than the control (15 %) group, and average weekly bus use was higher in the intervention (2.4 bus trips) compared to the control group (1.7). No intervention related adverse events were reported. Preliminary data from this COVID-impacted RCT to increase bus use through incentives demonstrated some evidence of effectiveness. A sufficiently powered trial that broadens participant reach and examines maintenance of longer-term behaviour change is warranted.