BACKGROUND: Intervention engagement is crucial in improving health outcomes and is an important modifiable factor in optimizing effectiveness. This study examined the engagement patterns and associated characteristics among people recently quit smoking in a mobile relapse prevention messaging intervention.
METHODS: This was a secondary analysis of a randomized controlled trial (ClinicalTrial.gov: NCT05370352) conducted in two government-funded cessation services in Hong Kong. Participants were 295 service users (77.6% male, mean age 46.7) who had recently quit smoking for 3 to 30 days and randomised to the intervention group from Mar 2023 to August 2024. They received personalized chat messaging support by a live counsellor for preventing relapse via WhatsApp for 3 months. Intervention engagement was defined as responses (yes/no) to each of the 18 regular messages sent to the participants over the 3-month intervention period for initiating real-time chat support. Group-based trajectory modelling was used to identify the engagement patterns over time. One-way analysis of variance and Chi-square tests were used to compare the baseline characteristics across engagement patterns. Ordinal logistic regression was used to examine the baseline characteristics associated with engagement levels.
RESULTS: We identified 5 distinct engagement patterns: disengaging (92 [31.2%]) where participants showed no engagement throughout; sharp-declining (52 [17.6%]), with engagement only at the beginning; parabolic-declining (64 [21.7%]), where engagement started high but declined over time; fluctuating (57 [19.3%]), maintained moderate-to-high engagement with variations; and active (30 [10.2%]), engagement sustained high throughout. The active group included a higher proportion of participants aged 50 years or older. Participants in sharp-declining and active groups reported higher daily cigarette consumption. Perceived greater confidence in quitting was significantly associated with higher engagement levels.
CONCLUSIONS: Five engagement patterns were identified among people recently quit smoking in a mobile relapse prevention messaging, with perceived confidence in quitting significantly associated with higher engagement levels.