The present study is a large-scale (n=1,600) single-blind, remote, parallel, randomized
clinical trial (RCT) comparing our app, the SiS app, to the NCI's smartphone app
"QuitGuide". The RCT will be conducted entirely remotely, because the app is intended to
be accessible to smokers nationally without need for in person contact. All participants
will set a targeted smoking cessation quit date and will be instructed to use the
provided app for 7 weeks, 1 week prior to and 6 weeks post-quit. Online surveys will be
conducted at enrollment and follow-up occurring 2 weeks, 6 weeks, 3 months, 6 months and
12 months after the initially chosen quit date. The primary outcome measure will be
30-day point-prevalence abstinence (PPA) at 6 months post-quit. The investigator team
developed the app, "Smiling instead of Smoking (SiS)," specifically for and in
collaboration with people who smoke less than daily. This app uses a positive psychology
approach, in line with their preference to focus on positive self-identity and wellness.
The investigators have rigorously and iteratively developed and tested this app in a
series of small scale prior studies. Study 1 (2017P001106) demonstrated feasibility and
acceptability when smokers were onboarded in person. Study 2 (2018P002699) demonstrated
feasibility and acceptability when smokers were onboarded remotely, nationwide. Study 3
(NCT04672239) demonstrated the app's ability to engage nondaily smokers and showed
proof-of-concept efficacy in a small, randomized trial, where participants using the SiS
app had significantly higher self-efficacy, lower craving, and higher positive affect at
the end of treatment, compared to controls.
In this large-scale efficacy trial, the primary outcome measure will be 30-day
point-prevalence abstinence (PPA) at 6-month post quit. The aims of the study are:
Aim 1: Test the effectiveness of the SiS app to improve smoking cessation outcomes
H1: 30-day PPA six months post quit will be higher for SiS compared to QuitGuide
participants.
H2: SiS participants will have higher 30-day PPA at end of treatment and 12 months
post quit.
Aim 2: Examine mechanisms and moderators of change
Using mediation modeling, the investigators will test if theorized mechanisms of
change (i.e., self-efficacy, positive affect, or craving) account for observed
effects on 30-day PPA six months post quit.
(Exploratory aim:) Using moderated mediation models, the investigators will examine
if socioeconomic status, race, and/or the presence of mental health conditions
moderate the effectiveness of SiS or moderate the mediation effects outlined in aim
2a.
Exploratory Aim 3: Explore app usage patterns and their relationship to smoking cessation
The investigators will identify patterns of overall app use, as identified by
group-based trajectory modeling.
The investigators will conduct a feature-level analysis of the apps (i.e., which
features got used how often).
The investigators will test if patterns of app use and/or feature use predict 30-day
PPA six months post-quit.
If found to be efficacious, this study would provide the first evidence of an efficacious
treatment (the SiS app) for people who smoke less than daily, for whom currently no
treatment guidelines exist.