Chat-based instant messaging support combined with brief smoking cessation interventions for Chinese community smokers in Hong Kong: Rationale and study protocol for a pragmatic, cluster-randomized controlled trial

Background: Novel approaches to engage community smokers in smoking cessation are needed as smokers typically lack motivation to quit or use evidence-based tobacco dependence treatment. Mobile instant messaging apps (e.g., WhatsApp, Facebook Messenger) are widely used but under-studied as a mobile health modality for delivering smoking cessation support. This paper presents the rationale and study design of a trial which aims to evaluate the effectiveness of a chat-based intervention using mobile instant messaging combined with brief interventions for community smokers. Methods: This is a two-arm, parallel, accessor-blinded, pragmatic cluster-randomized controlled trial on an estimated 1172 daily cigarette smokers aged ≥18 years proactively recruited from 68 community sites (cluster) throughout Hong Kong. Subjects in intervention group received three months of chat-based, instant messaging support guided by acceptance and commitment therapy and other behavioural change techniques, integrated with brief advice and active referral to a smoking cessation service using the AWARD (Ask, Warn, Advise, Refer, Do-it-again) intervention model. Control group received brief advice to quit plus a self-help booklet at baseline. Outcomes were assessed at 1-, 2-, 3- and 6-month after baseline. The primary outcome is abstinence validated by exhaled carbon monoxide (<4 ppm) and salivary cotinine (<10 ng/mL) at 6-month after baseline. Primary analyses will be based on intention-to-treat. Comments: This is the first trial examining the effectiveness of a chat-based cessation support programme combined with brief interventions in promoting abstinence. The intervention model can be adapted for other behavioural change treatments and more advanced digital smoking cessation intervention.