Sample and recruitment
Eligible individuals were US adults aged 21 years and older who had smoked at least 100 cigarettes in their lifetime, now smoke cigarettes “every day” or on “some days,” and had purchased their first JUUL vaporizer Starter Kit from a US retail store or through JUUL Labs Inc.’s e-commerce store at www.juulvapor.com within the past 7 days. Individuals were eligible to participate whether or not they intended to use a JUUL as an aid to quitting smoking. Eligibility in response to each criterion was self-reported, with the exception of being aged 21 years or over, which was verified by Veratad Technologies’ age verification software, AgeMatchSM at the point of an attempted online purchase. A JUUL Starter Kit contains a JUUL vaporizer, a USB charging dock, and one pod in each of four flavors (1× Virginia tobacco, 1× mint, 1× mango, and 1× crème). Each e-liquid pod sold in a JUUL Starter Kit contains 0.7 mL e-liquid and is designed to contain 41 mg of nicotine (59 mg/ml nicotine).
Individuals were invited to participate in this study in two ways. First, JUUL Labs Inc. sent email invitations to 37,536 age-verified adults who had purchased a JUUL vaporizer Starter Kit through JUUL’s e-commerce store between 4 April 2018 and 25 June 2018. The email invited individuals to participate in a 6-month online survey study about their use of combustible cigarettes, JUUL vaping products, and other brands of e-cigarettes and vaping products. Invitations were sent to the email address associated with a customer’s age-verified account. An email invitation containing the web-link to the baseline survey was scheduled to be sent to each individual approximately 4 days after they completed their online purchase of a JUUL Starter Kit so as to be received by the individual within 48 h after the scheduled delivery of their purchased product(s).
Second, individuals who purchased a JUUL vaporizer Starter Kit in a retail store were invited to participate via 3″ × 2.5″ cards that were manually inserted into the packaging of 500,000 JUUL vaporizer Starter Kits, which were then distributed at random to approximately 10,000 licensed store retailers of JUUL vaporizer products across the USA. Starter Kits containing invitation cards were distributed across April 2018. The invitation cards contained within these Starter Kits were used to recruit new JUUL purchasers to several research studies in addition to the present study. It is not known how many of the Starter Kits containing invitation cards remain unsold on store shelves.
Printed on each invitation card insert were the invitation text, the survey web address, and a unique six-digit alphanumeric code. Individuals who purchased a JUUL vaporizer Starter Kit that contained an invitation card insert were invited to type the survey web address—survey.juul.com—into their web browser, and then, when prompted, type the six-digit code displayed on their invitation card insert. Entry of a valid code routed the individual to an Account Creation webpage, and then to the study Informed Consent Form. Each six-digit code was valid for one entry; attempts to re-use the code were blocked. Requiring the entry of a unique, one-time access code ensured that only individuals who had purchased a JUUL vaporizer Starter Kit in a retail store could proceed to the Account Creation webpage, and requiring individuals to create a user account ensured that only one survey could be completed per account.
The first page of the survey displayed an Informed Consent Form (available upon request), which described the purpose of the survey, the names and contact details of the study investigators, information about who is eligible to take part and how survey data will be used, assurances of participant anonymity and confidentiality, and the source of funding for this study. Participants were informed they were being invited to take part in six monthly online surveys about their use of combustible cigarettes, JUUL vaporizer products, and other e-cigarettes and vapor products. Individuals who satisfied eligibility criteria and gave informed consent to participate began the survey. Participants were routed to questions that were applicable to them on the basis of a response or combination of responses to a previous question or questions. The survey instrument was designed with the assumption that all respondents to a question would be asked the next question, unless there were specific instructions routing a subgroup of respondents to a different question. Participants answered survey questions at their own pace. If a participant did not complete the survey, all data provided up to the point of exit from the survey was excluded from analysis.
The baseline survey took around 15 min to complete. Participants who completed the baseline survey received an automated email invitation to complete a follow-up survey 30 ± 5 days, 60 ± 5 days, 90 ± 5 days, and 180 ± 5 days after completion of the baseline survey. Two reminder emails were sent to non-respondents within each 10-day window. Participants received a USD$30 virtual Visa Reward Card by email for each survey they completed.
Cigarette smoking in the past 30 days
The primary outcome measure in this study was self-reported past 30-day abstinence from cigarette smoking, which was determined at each assessment by a “No” response to the question, “In the past 30 days, have you smoked a cigarette, even one or two puffs?” Participants who indicated they have smoked a cigarette in the past 30 days were asked two further questions about their frequency of smoking in the past 30 days—“Do you now smoke cigarettes…” (every day, some days, not at all), and “On how many of the past 30 days did you smoke cigarettes?” (numeric response, 1–30), and one question about their intensity of smoking in the past 30 days—“On those days that you did smoke, how many cigarettes did you usually smoke each day? A pack usually has 20 cigarettes in it”. Participants who did not provide answers to these four questions at the baseline assessment were excluded from the analytic sample.
Cigarette smoking history
Questions assessed the age at which participants first smoked a cigarette, first started smoking regularly, the number of months/years for which participants had been smoking cigarettes regularly, and the number of cigarettes participants had smoked in their lifetime.
Use of a JUUL vaporizer and JUULpod flavors in the past 30 days
Questions assessed the number of days in the past 30 days on which participants had used a JUUL vaporizer and the total number of JUUL vaporizer refill pods they had consumed in each of eight commercially available flavors (Virginia tobacco, mint, mango, crème, fruit, cucumber, classic tobacco, and menthol) in the past 30 days. Participants were coded as a “primary user” of a specific flavor of JUULpods when they reported having consumed more pods in that flavor than in any other flavor. For example, a participant who reported having consumed 10 mango-flavored JUULpods and 5 mint-flavored JUULpods in the past 30 days would be coded as a primary user of mango-flavored JUULpods.
Participants were coded as “past 30-day exclusive users of tobacco flavors” if they reported use of only Virginia tobacco- and/or classic tobacco-flavored JUULpods in the past 30 days. Participants were coded as “past 30-day exclusive users of characterizing flavors” if they reported use of only mint-, mango-, crème-, fruit-, cucumber-, and/or menthol-flavored JUULpods in the past 30 days. Participants were coded as “past 30-day users of both tobacco and characterizing flavors” if they reported consumption of at least one pod in Virginia tobacco or classic tobacco flavor and at least one pod in mint, mango, crème, fruit, cucumber, or menthol flavor.
Use of e-cigarettes other than a JUUL vaporizer in the past 30 days
Participants were asked if they had used any brand of e-cigarette or vaping device other than a JUUL vaporizer in the 30 days prior to each assessment.
Reasons for purchasing and using a JUUL vaporizer Starter Kit
At the baseline assessment, participants were asked to identify which, if any, of a list of health, social, financial, sensory, and convenience reasons were reasons why they first decided to purchase a JUUL Starter Kit.
Questions assessed sex, age, race/ethnicity, educational attainment, annual household income, and census region of participants’ residence.
Rates of past 30-day abstinence from smoking at the 3-month and 6-month follow-up assessments are reported for the intention-to-treat (ITT) sample (N = 15,456) that completed the baseline assessment. At each follow-up assessment, participants with a missing response to the question “In the past 30 days, have you smoked a cigarette, even one or two puffs?” were recoded as “smoked in the past 30 days” under the worst-case scenario assumption that these participants had returned to baseline patterns of cigarette smoking.
Rates of past 30-day abstinence from smoking at the 3-month and 6-month follow-up assessment are also reported for efficacy subsets of participants who provided smoking data at the 3-month assessment (n = 9272, 60.0% of the ITT sample) and the 6-month assessment (n = 9040; 58.5% of the ITT sample), respectively. A rate of past 30-day abstinence from smoking at both the 3-month assessment and the 6-month follow-up assessment is also reported for an efficacy subset of 7726 participants comprising those who provided smoking data at both the 3-month assessment and at the 6-month assessment. Rates of past 30-day point prevalence abstinence from smoking observed in the ITT sample and in the efficacy subset samples were considered as lower and upper bound estimates of the rates of past 30-day point prevalence abstinence from smoking at each follow-up assessment.
Factors associated with past 30-day abstinence from smoking at the 6-month assessment were examined through two logistic regression models, with each model conducted in two steps. In model 1 step 1, six demographic variables (age, sex, race/ethnicity, annual household income, education level, and US census region), four smoking history variables (age of first smoking, lifetime years of regular smoking, number of smoking days in the 30 days prior to the baseline assessment, number of cigarettes smoked per day in the 30 days prior to the baseline assessment), one e-cigarette use variable (past 30-day use of a secondary e-cigarette), and four JUUL use variables (place of first JUUL purchase, number of days of JUUL use in the past 30 days, primary JUULpod flavor used in the past 30 days, and having purchased a JUUL vaporizer to help quit smoking) were entered as predictor variables. To assess the extent to which the effect of participants’ primary use of JUULpod flavors on past 30-day abstinence from smoking at the 6-month assessment was moderated by the place at which participants purchased their first JUUL Starter Kit, an interaction term for “primary JUULpod flavor use”*“place of first purchase of a JUUL Starter Kit” was entered at step 2. Model 2 replicated model 1 with the exception that the variable “primary JUULpod flavor used in the past 30 days” was replaced by the variable “JUULpod flavors used regularly in the past 30 days” (exclusive use of JUUL tobacco flavors vs. exclusive use of JUUL characterizing flavors vs. use of flavors from both categories).
Odds ratios are reported unadjusted and adjusted for the effects of other variables in the model. Odds ratios in these regression models indicate the proportionate change in a participant’s odds of self-reporting past 30-day abstinence from smoking associated with the indicator on the categorical predictor variable. Analyses were conducted using SPSS, v. 25.0. p values < 0.05 were considered statistically significant.