The aim of the present two-armed randomized controlled trial is to test the efficacy of
Detour, a smartphone game to help youth (16-25 years) quit smoking. It is designed to be
an accessible, multi-component intervention providing in-the-moment distractions from
cravings. First, Detour targets stimuli devaluation using a gamified go/no-go training in
an endless runner game format. Second, the researchers aimed to reduce delay discounting
in two ways; 1) players can replace neutral images in the go/no-go training with positive
images from their own lives related to their future self; 2) players can set and monitor
personal goals via the game, to promote future-self priming. Third, participants join a
social shell comprising Instagram and TikTok content to provide psychoeducation about
quitting smoking and to interact with fellow players who quit simultaneously. Finally,
the timing and content of in-game messaging is personalized to each participant based on
information provided in an ecological momentary assessment component and a stop plan
filled out during the week before the quit attempt.
Detour will be tested against a self-help digital brochure, "Jouw eigen plan om te
stoppen met roken" by the Trimbos Institute, the Netherlands. The brochure provides
guidelines to independently design a stop-plan including questions about seeking support
from others, strategies to fight cravings, and setting rewards for milestones after
quitting. Additionally, the brochure has psychoeducational information that is valuable
when planning to quit smoking.
For the data collection procedure, the researchers will first broadly distribute a short
screening questionnaire via educational institutes and social media to assess study
inclusion criteria. Eligible participants will be contacted by phone/text message/email
to explain the purpose of the study further and invited to fill out the pre-test
measurement if they would like to participate. The researchers will recruit nationwide
and strive for a diverse sample in terms of gender, demographic location and educational
levels. Participants will provide informed consent at both the screening and pre-test
phases.
After the pre-test, blocks of 6 participants are randomly assigned to either the "Detour"
game group or the brochure group to begin the intervention. The intervention period lasts
for five weeks. During week 0 or the preparatory week, participants can access Detour or
the brochure but have not yet quit. On day 1 of week 1, known as quit day, participants
will quit smoking and try to remain smoke-free for the next four weeks (weeks 1-4).
The target sample size is N = 604, with 10% drop-outs taken into account. Recruitment
will stop once 604 participants have received an intervention or on August 1, 2025.
The aim is to achieve 25% abstinence rates at 6-month follow-up in the game group. The
researchers aim to prove a small effect size (odds ratio 1.88) with 90% power. A power
analysis (logistic regression analysis, one-tailed alpha .05, and a fifty-fifty
distribution of participants in both groups) showed that they will need N = 604
participants, taking into account a 10% loss.
To assess the immediate effectiveness of the game for smoking cessation in youth,
logistic regression analyses will be performed with intervention group (game or
brochure), as predictor and 14-day point prevalence of smoking abstinence (yes/no) at
6-month follow-up as the outcome. Age, Gender, socioeconomic status (SES), and baseline
weekly smoking will be added to the model as controlled variables.
To assess the longer-term effectiveness of the game for smoking cessation in youth,
logistic regression analyses will be performed with intervention group (game or
brochure), as predictor and 14-day point prevalence of smoking abstinence (yes/no) at
post-test as the outcome. Age, Gender, socioeconomic status (SES), and baseline weekly
smoking will be added to the model as controlled variables.
To assess the effect of the game on weekly smoking, multilevel regression analysis will
be performed with intervention group (game or brochure), time (pre-test, post-test,
3-month follow-up and 6-month follow-up), and their interaction as predictors, and weekly
smoking as the outcome. The following models will be tested. Age, Gender, socioeconomic
status (SES), and baseline weekly smoking will be added to the model as controlled
variables.
Model0 ← WeeklySmoking ~ (1 | ID); check intra-class correlations
Model1 ← WeeklySmoking ~ TreatmentGroup + Time + Gender + Age + SES + Baseline
weekly smoking + (1 | ID)
Model2 ← WeeklySmoking~ TreatmentGroup + Time + Gender + Age + SES + Baseline weekly
smoking + (1 + time | ID); compare model 1 and model 2 to see if random slopes give
better model fit.
Model3 ← WeeklySmoking~ TreatmentGroup + Time + TreatmentGroup:Time + Gender
- Age + SES + Baseline weekly smoking + (1 + time | ID); Calculate simple slopes
for both cases of treatment group.
For the analyses of the primary and secondary outcomes, a one-tailed p < .05 criteria
will be used. For remaining analyses the standard p < .05 criteria will be used.
Furthermore, the intention to treat approach will be used, where it is assumed that
people who missed post-test or either follow-up are non-abstinent.
Participants who only responded to the pretest but neither post-test, 3-month follow-up,
nor 6-month follow-up will be considered as relapsers in analyses with abstinence as the
outcome. In models with weekly smoking as the outcome, the majority of weekly smoking
values would need to be imputed, so instead participants who only responded to the
pre-test measure will be excluded.
The present pre-registration only pertains to the efficacy of the intervention. A
follow-up registration on the in-depth analysis of the intervention effects and sub-group
analyses to test who the intervention worked best for will be made. Please refer to the
project page for more information (https://osf.io/k784a/).