Questions about quitting (Q2): design and methods of a Multiphase Optimization Strategy (MOST) randomized screening experiment for an online, motivational smoking cessation intervention.

Effective interventions are needed to improve smokers' motivation for quitting, treatment utilization, and abstinence rates. The Internet provides an ideal modality for delivering such interventions, given the low cost, broad reach, and capacity to individually tailor content, but important methodological questions remain about how to best design and deliver an online, motivational intervention to smokers. The current paper reports on the intervention, study design and research methods of a randomized trial (called Questions about Quitting) designed to address some of these questions. Using a Multi-phase Optimization Strategy (MOST) screening experiment, the trial has two key aims: to examine the impact of four experimental intervention factors (each evaluated on two levels) on smokers' subsequent treatment utilization and abstinence, and to examine select moderators of each sub-factor's effectiveness. The experimental factors of interest are: navigation autonomy (content viewing order is dictated based on stage of change or not), use of self-efficacy based testimonials (yes vs. no), proactive outreach (reminder emails vs. no emails), and decisional framework (prescriptive vs. motivational tone). To our knowledge, this is the first application of the MOST methodology to explore these factors or to explore the optimal design for a motivational intervention targeting smokers not actively trying to quit smoking. The rationale for the experimental factor choice, intervention design, and trial methods are discussed. Outcome data are currently being collected and are not presented, but recruitment data confirm the feasibility of enrolling smokers at varying stages of readiness to quit.