Effect of a workplace mobile phone-based instant messaging intervention on smoking cessation: a cluster-randomized controlled trial.

Aims: To test the effectiveness of intractive, instant messaging chat-based mobile phone support versus text-based mobile phone support integrated with brief interventions on self-reported smoking abstinence in workplaces.

Design: A two-arm parallel cluster-randomized controlled trial with follow-up to 12 months.

Setting: Seventy-five companies in Hong Kong, China.

Participants: Daily cigarette adult smokers (92.0% male, 90.9% not ready to quit within the next 30 days) from 75 companies (clusters).

Interventions: Participants were cluster-randomized to receive text-based support (TBS, n = 375; 38 clusters) or chat-based support (CBS, n = 304; 37 clusters). TBS participants received automated and fix-scheduled text messages on cessation advice and support. CBS participants received fix-scheduled text messages and additional real-time psychosocial and cessation support via instant messaging services (e.g. WhatsApp) by counsellors. Both groups received a 1-hour health talk at baseline and brief telephone counselling at 1 week and 1, 3, 6 and 12 months.

Measurements: The primary outcome was self-reported 7-day point-prevalence abstinence at 6 months post-treatment initiation. Secondary outcomes included 7-day point-prevalence abstinence at 12 months, repeated 7-day point-prevalence abstinence, smoking reduction, quit attempts and intervention engagement, defined as having read text messages and/or engaged in conversation with counsellors.

Findings: By intention-to-treat assuming that dropouts were smoking, self-reported abstinence was not significantly different between the CBS and TBS groups at 6 months [18.8 versus 21.6%, risk ratio (RR) = 0.87, 95% confidence interval (CI) = 0.61, 1.23, retention = 71.3%] and 12 months (21.4 versus 24.0%, RR = 0.90, 95% CI = 0.66, 1.21, retention = 70.8%). The repeated 7-day point-prevalence abstinence, smoking reduction and quit attempts were similar between the groups. The participants who were engaged in the text- and/or chat-based interventions had greater abstinence (adjusted RR = 2.91, 95% CI = 1.87, 4.52) at 6 months compared with unengaged participants.

Conclusions: Compared with a text messaging mobile phone intervention, a chat-based instant messaging mobile phone intervention did not improve smoking abstinence over 12 months in workplaces. Engagement in text-based or chat-based interventions was associated with higher quit rates compared with non-engagement.