JMIR Publications

ABSTRACT

Background:

Smoking remains a leading cause of preventable death and illness worldwide. Internet interventions for smoking cessation have the potential for enormous public health impact given their broad reach and proven effectiveness. Given the dose-response association between engagement and behavior change outcomes, identifying strategies to promote engagement is a priority across digital health interventions. Text messaging is a proven smoking cessation treatment modality and also a powerful strategy to increase intervention engagement in other areas of health, but it has not been tested as an engagement strategy for a digital cessation intervention.

Objective:

To examine the impact of four experimental text message features on adult smokers’ engagement with an Internet smoking cessation program.

Methods:

Guided by Multiphase Optimization Strategy (MOST) principles, we conducted a 2x2x2x2 full factorial screening experiment in which 864 participants were randomized to one of 16 conditions, after registering with a free Internet smoking cessation program and enrolling in its automated text message program. Experimental factors were personalization (On/Off), integration between the web and text message platforms (On/Off), dynamic tailoring of intervention content based on user engagement (On/Off), and message intensity (Tapered vs. Abrupt dropoff). Primary outcomes were 3-month measures of overall engagement (pageviews, time on site, return visits to the website) as well as use of six interactive features of the Internet program. All metrics were automatically tracked; there was no missing data.

Results:

Main effects were detected for Integration and Dynamic Tailoring. Integration significantly increased interactive feature use by participants, while dynamic tailoring increased the number of features used and pageviews. No main effects were found for message intensity or personalization alone, though several synergistic interactions with other experimental features were observed. Synergistic factor effects when all four experimental components were active resulted in the highest rates of interactive feature use and the greatest proportion of participants at high levels of engagement. Measured in terms of standardized mean differences (SMD), effects on interactive feature use were highest for Build Support System (.56; 95% CI=.27, .81), Choose Quit Smoking Aid (.38; 95% CI=.10, .66), and Track Smoking Triggers (.33; 95% CI=.05, .61). Among the engagement metrics, the largest effects were on overall feature utilization (.33; 95% CI=.06-.59) and time on site (.29; 95% CI=.01-.57). Since no SMD>.30 was observed for main factor effects on any outcome of interest, results suggest that, for at least some outcomes, the combined intervention was stronger than individual factors alone.

Conclusions:

This factorial experiment demonstrates the effectiveness of text messaging as strategy to increase engagement with an Internet smoking cessation intervention, resulting in greater overall intervention “dose” as well as greater exposure to the core components of tobacco dependence treatment that can promote abstinence. Clinical Trial: ClinicalTrials.gov NCT02585206