Building Capacity and Promoting Smoking Cessation in the Community Via "Quit to Win" Contest 2024: a Randomised Controlled Trial of a Brief Behavioural Economic Intervention

Smoking cessation services are free and effective but underused in Hong Kong. Active referral to smoking cessation services has consistently been found effective in promoting service use and successful quitting as a stand-alone strategy or when combined with other interventions. Participants who received active referral are introduced about the cessation services in Hong Kong and offered connection to the services of their choices. Contacts of participants who agreed to be referred are transferred to the selected cessation providers, who will subsequently contact the participants for further treatment.

The current active referral intervention uses an opt-in approach, where participants are required to actively choose to be connected to the services. By leveraging behavioural economic principles, a simple yet promising strategy to strengthen the active referral intervention is to utilize an "opt-out" approach, where participants are automatically referred to the service unless they actively decline the referral. By making referral to smoking cessation services as the default choice, the investigators aim to increase the uptake of these services and thus improve smoking cessation outcomes. Additionally, mobile messaging informed by behavioural economics principles can serve as nudges to prompt smokers to initiate quitting and utilise cessation services.

The clinical trial aims to test the effectiveness of opt-out referral, with or without behavioural economic-based mobile messaging, compared to opt-in referral, in promoting smoking cessation. The trial will be nested within the 15th "Quit to Win" Smoke-free Community Campaign organised by the Hong Kong Council on Smoking and Health.