Impact of E-Cigarette Prevention Messages on Adolescents
Phase: NA
Conditions: Vaping Behavior
Sponsor: UNC Lineberger Comprehensive Cancer Center

 
 
 
 
Impact of E-Cigarette Prevention Messages on Adolescents 
Study Protocol 
NCT#05985538 
Version Date: 6/25/2020 
 
 
 

Participants 
We recruited adolescents living in the United States (US) from a national probability-
based panel administered by NORC. This panel consists of households randomly selected from a 
sample frame, with a known, non-zero probability of selection from NORC’s National Frame. 
The frame provides at least 97% sample coverage of the US population by supplementing the US 
Postal Service Delivery Sequence File. To recruit adolescents aged 13-17, NORC first contacted 
a parent or guardian to obtain parental consent, followed by eligible adolescents being invited to 
participate in the study. Young adults aged 18-20 were invited directly to participate. The 
eligibility criteria included: being aged 13 to 20 years, possessing a phone capable of sending 
and receiving text messages, and either having used e-cigarettes or vapes in the past 30 days or 
being susceptible to vaping. Susceptibility was defined as answering anything other than 
“definitely not” or “not at all curious” to any of five susceptibility questions that were answered 
on four-point scales (1 = Definitely not, 4 = Definitely yes; 1 = Not at all curious, 4 = Very 
curious). An example item is, “Do you think you might use an e-cigarette or vape soon?” Our 
target sample size was 506, accounting for up to 20% loss to follow-up. The trial had 80% power 
to detect an effect size of d=.28 or larger between the intervention arm and the control arm.  
 
Recruitment took place from February 5 to June 2 of 2024. For adolescents aged 13-17, 
legal parents or guardians provided informed parental consent online, and adolescents provided 
assent online before beginning the surveys. For young adults aged 18-20, participants provided 
informed consent online before beginning the surveys. Of the 733 adolescents and young adults 
screened, 183 were ineligible because they were not susceptible to vaping; 53 were ineligible 
because they did not have a phone that sends and receives text messages; 11 were ineligible 
because they lived in the same household as a current or prior study participant; and 6 met 

criteria but declined to participate (Figure 1). This resulted in a total of N=480 adolescents and 
young adults enrolled in the trial. The trial was approved by the University of North Carolina 
Institutional Review Board and is registered at clinicaltrials.gov, identifier NCT05985538 
(https://www.clinicaltrials.gov/ct2/show/NCT05985538). This paper follows CONSORT 
reporting guidelines for RCTs.  
Procedures 
Trial design and protocol. We conducted a two-arm randomized controlled trial (RCT) 
with parallel assignment. At the start of the trial, participants were randomly assigned to either 
Breaking Vape, a vaping prevention text message program (intervention arm) or to Texting for 
Wellness, a wellness text message program (attention control arm). Randomization was 
performed without replacement using simple randomization methods based on random numbers 
generated R Studio version 4.0.4. Due to the nature of the interventions being administered 
online, the research team was not blinded post-assignment.  
Participants in both trial arms received at least one (but typically two) text messages per 
day over a 28-day period, with introductory messages sent on day 1 and concluding messages 
sent on day 28. The messages sent on days 2 – 27 focused on a series of topics in the intervention 
(negative consequences of using e-cigarettes and vaping) or attention control (wellness 
information) arms. To enhance engagement in both trial arms, some messages prompted replies 
from participants through multiple-choice quizzes and true/false questions (i.e., two-way 
messages). Additionally, some messages included website links to supplement the text message 
program information. For the intervention arm, we developed a website specifically for this 
study (https://www.breakingvape.org), while for the control arm, we provided links to existing 
teen wellness websites (e.g., https://kidshealth.org/). The structure of the intervention and control 

arms were matched on the 28-day duration of the program and the number and types of two-way 
messages sent. In both intervention and control arms, messages were sent at approximately 4 
p.m. local time. For multiple-choice quizzes and true/false questions, if participants did not 
respond, the correct answer was sent to them at approximately 7 p.m. local time. Consistent with 
the rules required by cell phone carriers, participants could opt out of receiving messages at any 
time by texting “Stop” and could rejoin the program by texting “Start.” A technical document 
describing the text messaging programs is included in the supplemental file. 
To assess primary and secondary outcomes, participants completed four online surveys at 
four intervals: baseline, mid-intervention (2 weeks; survey was open from days 12 - 16), end of 
intervention (4 weeks; survey was open from days 29 - 36), and follow-up (8 weeks; survey was 
open from days 57 - 70). These surveys were sent by NORC via email, with text message 
reminders as needed (reminders were sent from a different number than the intervention 
messages). Incentives were offered in the form of points, redeemable for a total cash equivalent 
of up to $120 upon completing the trial ($20 for the first survey, $25 for each of the second and 
third surveys, $30 for the final survey, and $1 for each text message response, up to $20). 
Intervention messages. Each vaping prevention text message in the Breaking Vape 
program focused on one of six topics. The program was designed so that messages about three 
topics were delivered before the wave 2 survey: nicotine addiction (days 2 – 5), monetary costs 
of vaping (days 6 – 8), chemical exposures from e-cigarette vapor (days 9 – 13); messages about 
the other three topics were delivered after the wave 2 but before wave 3 survey: cosmetic effects 
of vaping (days 14 – 16), mental and physical use symptoms of vaping (days 17 – 22), and health 
impact on organs from vaping (days 23 – 27). These topics were selected based on a series of 
studies that examined which vaping prevention content most resonated with youth.1,2 This 

process culminated in the testing of a series of text statements that were subsequently adapted for 
the vaping prevention intervention.3 An example message from Breaking Vape is “True or false? 
Vaping is much less addictive than smoking cigarettes.” If a participant texted “True” (the 
incorrect answer), the program would respond with: “Actually, false is the right answer. Vaping 
can be as addictive as smoking cigarettes, and some vaping devices have even more nicotine than 
cigarettes. That’s why vaping is so easy to get hooked on.”  
Attention control messages. Each wellness text message in the Texting for Wellness 
program focused on one of six topics, in the following order: sleep hygiene, safe driving, sun 
safety, study habits, nutrition, and exercise. These were chosen as they were relevant to youth 
but were unrelated to substance use behaviors, with content adapted from several youth-oriented 
wellness websites. An example message from Texting for Wellness is “True or false? People who 
eat breakfast do better in school.” If a participant texted “True” (the correct answer), the program 
would respond with: “You got it! Breakfast is an important part of your morning, and fueling 
your body before school can help you perform better.” 
Text message delivery. A total of 27,840 text messages were intended to be sent out 
during the study. Because of intermittent technical issues in text message delivery, as well as a 
modest number of participants texting “stop” during the study (which halted all text message 
delivery unless participants texted restart), not all messages were delivered. In total, 26,100 
messages were successfully delivered, representing a 93.8% fidelity rate (26,100/27,840). Text 
message delivery did not differ by trial arm, with a fidelity rate of 93.6% for Breaking Vape 
messages and 93.9% for attention control messages. 
 
Intervention engagement. Of the text messages sent out, 20 of them asked for a response 
from the participant. Across all participants, the number of responses varied from 0 – 20 (M= 

12.33, SD=7.56; Median=16). The number of responses was similar between Breaking 
Vape (M=12.19, SD=7.71, Median=16) and attention control (M=12.46, SD=7.41; Median=16) 
trial arms. Across conditions, a small proportion of participants did not respond to any messages, 
including 16.7% (n=40) in Breaking Vape and 12% (n=29) in the attention control group. In 
addition, we asked participants (in the 2 and 4-week surveys) how many of the text messages 
they read, on a 5-point response scale: 1 (none), 2 (a few), 3 (some), 4 (most), or 5 (all). In the 
first 2 weeks of the text-messaging, 88.1% in the Breaking Vape trial arm and 83.7% in the 
attention control arm reported reading “most” or “all” of the messages, while in the latter 2 
weeks of the text-messaging, 85.5% in the Breaking Vape trial arm and 83.9% in the attention 
control arm reported reading “most” or “all” messages. We also asked participants how many of 
the weblinks in the text messages they visited. In the first 2 weeks of the text-messaging, 60.6% 
in the Breaking Vape trial arm and 47.2% in the attention control arm reported visiting at least 
one (of three possible) weblinks embedded in the text messages, while in the latter 2 weeks, 
65.6% in the Breaking Vape trial arm and 57.6% in the attention control arm reported visiting at 
least one (of three) possible weblinks. 
Measures 
At baseline, participants reported vaping and smoking behaviors, susceptibility to vaping 
and smoking, vaping and smoking attitudes and beliefs, and demographic characteristics. At 
mid-intervention (wave 2 survey, at 2 weeks) and end of intervention (wave 3 survey, at 4 
weeks), participants reported vaping and smoking behaviors, susceptibility to vaping and 
smoking, vaping and smoking attitudes and beliefs, and questions about reading and engaging 
with the text messages. At follow-up (wave 4 survey, 8 weeks after baseline), participants 

reported vaping and smoking behaviors, susceptibility to vaping and smoking, and vaping and 
smoking attitudes and beliefs. 
Primary outcome. Susceptibility to vaping at the end of text messaging (wave 3 survey, 
at 4 weeks) was the primary trial outcome. Susceptibility prospectively predicts vaping behavior, 
4,5 including when operationalized as a scaled score where higher values predict both greater 
initiation and current use of vapes.4 We assessed susceptibility with a 3-item susceptibility to 
vaping scale, similar to other studies. 6–9 This scale assesses the extent to which adolescents are 
open to vaping, with a 4-point response scale ranging from “definitely not” (coded as 1) to 
“definitely yes” (coded as 4). We calculated a susceptibility score by averaging the 3 items, with 
higher scores representing higher susceptibility to vaping (Cronbach’s α at baseline =.94).  
Secondary outcomes. The survey assessed several secondary outcomes hypothesized to 
elicit behavior change, according to the reasoned action approach 10. Response scales for 
secondary outcomes had five points, coded such that higher scores represented a greater amount 
of the construct. For multi-item scales, overall scale scores were of the average of the items.  
Vaping outcomes. Three-item scales assessed instrumental attitudes toward vaping 
(α=.89), affective attitudes toward vaping (α=.89), vaping addiction risk beliefs (α=.86, vaping 
monetary cost beliefs (α=.94), vaping chemical risk beliefs (α=.93, vaping cosmetic risk beliefs 
(α=.90), vaping physical symptoms of use beliefs (α=.85), vaping mental health symptoms of use 
beliefs (α=.93), vaping health organ risk beliefs (α=.91), vaping injunctive norms (α=.92), and 
vaping refusal self-efficacy beliefs (α=.91), 11–16. Participants were also asked to report the 
number of days they vaped over the past 30 days. Higher scores indicated more positive attitudes 
towards vaping, greater belief in the harms of vaping, a stronger perception of others’ 
disapproval of vaping, and a greater belief in one’s ability to refuse vaping in social situations.  

Smoking outcomes. Susceptibility to smoking cigarettes was assessed with a 3-item scale 
(α=.93) 17. Single items assessed smoking addiction risk belief, health harm risk belief, smoking 
instrumental attitudes and affective attitudes 11,16. Participants also reported the number of days 
they smoked cigarettes and used other tobacco products over the past 30 days.  
Covariates. Adjusted models controlled for gender (male (ref), female, or other identity), 
age (13-15, 16-17 (ref), or 18-20), race (white (ref) or other race), ethnicity (Hispanic or not 
(ref)), sexual orientation (straight (ref) or LGBTQ), parental education (less than high school, 
high school/GED, some college (ref), bachelor’s degree, or graduate school), and nicotine use in 
the home (no (ref) or yes). 
 
 

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