Abstract
Introduction:
The popularity of electronic cigarettes (ecigarette) has increased worldwide among youth, even in countries like Mexico that ban them. This study aimed to assess the correlates of ecigarette use frequency among Mexican students who currently use ecigarettes, as well as to describe their reasons for use.
Methods:
Data were analyzed from a school-based survey of 57 public middle schools from the three largest cities in Mexico. Primary analyses were confined to those who used e-cigarettes in the prior 30 days. Censored binomial models for truncated distributions were estimated, regressing lifetime and past month frequency of use on participant sociodemographics, other substance use (smoking, alcohol, drugs), technophilia, characteristics of e-cigarettes used, and family and friends use of nicotine products.
Results:
Being male (APR=1.93 95% CI 1.53-2.44), using drugs, (APR=1.51 95% CI 1.03-2.20), higher technophilia (APR=1.66 CI 1.21-2.29) and having a family member who uses e-cigarettes and cigarettes were associated with more frequent use in the last month. Use of fruit and combined flavors had used e-cigarettes more often in their lifetime compared to students who used mint/menthol flavors.
Conclusions:
Some risk factors for more frequent e-cigarette use among Mexican youth are similar to other countries (having relatives who use ecigarettes, using drugs, and use of fruit flavors). Additionally, we found a positive association between the novel measure of technophilia with frequency of e-cigarette use. The appeal of flavors, in particular, suggests the importance of reducing youth access to flavored products to impede product initiation and progression.
Keywords: E-Cigarette, Frequency, Motivations, Mexico, Adolescents
1. Introduction
The popularity of electronic cigarettes (e-cigarettes) has increased rapidly among youth around the world, even in countries that ban them (Glasser et al., 2017; Thrasher et al., 2016; US Department of Health, 2016; Czoli et al., 2014; Adkison et al., 2013). E-cigarette use among youth is a potential public health concern as several studies suggest that it is a “gateway” to combustible cigarette smoking initiation, including among youth who are at relatively low risk for smoking (Lozano et al., 2017; Wills et al., 2017; Barrington et al., 2016; Levanthal et al., 2015; Primack et al., 2015). On the other hand, results from national surveys suggest that the decrease in smoking prevalence in recent years among US youth coincides with an increase in e-cigarette use, suggesting that e-cigarette use may be displacing cigarette use (Levy et al., 2018).
Studies of adolescents have focused primarily on the correlates of trial and current use of e-cigarettes (i.e., any use in the last 30 days); however, in low- and middle-income countries (LMICs), little is known about factors associated with e-cigarette use frequency and motivations for use among more regular users. The current study aimed to understand these factors among middle-school students in Mexico, where e-cigarettes are banned yet the prevalence of e-cigarette trial and current use among adolescents is high and similar to that for conventional cigarettes (Barrientos et al., 2018; Zavala et al., 2018).
1.1. Frequency of E-Cigarette Use
Correlates of e-cigarette use frequency have been evaluated almost exclusively in high-income countries (HICs). Cross-sectional studies among adolescents and youth in the United States and South Korea have found that higher frequency of use in the last month was associated with combustible cigarette use (Lee et al., 2017; McCabe et al., 2017; Villanti et al., 2017; Warner et al., 2016; Neff et al., 2015). Frequency of use in the last month was also associated with impulsivity (Bold et al., 2017), receiving the first e-cigarette from a family member (Vogel et al., 2018), using a greater number of flavors (Morean et al., 2018), particularly sweet flavors (i.e., fruit and dessert) or alcohol flavors, using a customizable e-cigarette device (Vogel et al., 2018), and using e-cigarettes with nicotine (Miech et al., 2018; Vogel et al., 2018). A longitudinal study on adolescents’ e-cigarette use frequency found that for every level of increase in baseline self-reported nicotine concentration in e-cigarettes used (i.e., none, low, medium and high), there was an increase in e-cigarette use frequency at a six month follow up among high schoolers in California (Goldenson et al., 2017). Finally, more frequent e-cigarette use in the last year has been associated with drug and alcohol use (Dunbar et al., 2017).
1.2. Motivations for E-Cigarette Use
School-based studies in the US using nationally representative samples found that the primary motivations for e-cigarette use among middle schoolers were the availability of flavors (Tsai et al., 2016; Patrick et al., 2016), curiosity (Patrick et al., 2016), peer influence (Tsai et al., 2016) the belief that e-cigarettes are less harmful than combustible cigarettes (Tsai et al., 2016), and boredom (Patrick et al., 2016). A nationally representative survey of South Korean adolescents found that less frequent users of e-cigarettes (i.e., less than 3 days a month) were more likely to report curiosity as the main reason for use, while the main reasons among more frequent users (i.e., 10 or more days a month) were the desire to quit smoking and to use in places where smoking was prohibited (Lee et al., 2017).
1.3. Mexican Context
The importation, distribution, sales, and marketing of e-cigarettes are banned in Mexico (Camara de Diputados del H. Congreso de la Union 2008). Nevertheless, a nationally representative survey found that 6.5% of Mexican adolescents (12-17 years) had tried e-cigarettes, 1.1% were current e-cigarette users, and being a current smoker was a strong correlate of e-cigarette use (E-cigarette use: Nonsmokers 0.7%, Current smokers 9.1%) (Zavala et al., 2018). Furthermore, a cohort study of public middle school students in the three largest cities of Mexico (Guadalajara, Monterrey, Mexico City) found that 10% of first-year students had tried e-cigarettes at baseline (2015) (Thrasher et al., 2016), and, after 20 months of follow up, students who had tried e-cigarettes but not cigarettes at baseline were more likely to have tried combustible cigarettes than those who had not tried either product (Lozano et al., 2017). At follow up, 19% had tried e-cigarettes and 12% had used e-cigarettes in the prior month, which was similar to the prevalence of current smoking (11%), with 8% exclusively using e-cigarettes (Barrientos et al., 2018). Similar to studies in other countries, trial of e-cigarettes in Mexico was associated with higher sensation seeking, internet tobacco advertising exposure, and having friends and parents who smoke combustible cigarettes or use e-cigarettes (Barrientos et al., 2018; Thrasher et al., 2016;). Also, previous Mexican studies show that adolescents with higher levels of technophilia were more likely to try e-cigarettes (Barrientos et al., 2018; Thrasher et al., 2016). Technophilia is a positive orientation toward new technologies, emphasizing the pleasures and positive emotions that accompany the adoption of new technologies (Ronit et al., 2011).
The current study aimed to examine the correlates of e-cigarette use frequency (last month and lifetime) among Mexican adolescents who used e-cigarettes in the prior 30 days and to describe their motivations for use. Based on the research reviewed above, we hypothesized that higher frequency of e-cigarette use would be associated with the use of other substances (i.e., smoking, alcohol use, drug use), using e-cigarettes with nicotine, having a preference for sweet e-cigarette flavors, and having a family member who uses e-cigarettes. We also hypothesized that those who used e-cigarettes more frequently would be more likely to use them to avoid smoking cigarettes and to use e-cigarettes in smoke-free places. By contrast, we expected that students who use e-cigarettes less frequently would report curiosity as their main motivation for using e-cigarettes.
2. Methods
2.1. Study Population
Data come from a school-based sample of 8718 students surveyed in the last year of middle school in 57 public middle schools that were randomly selected from the three largest cities in Mexico (Mexico City, Guadalajara, and Monterrey). A detailed description of school selection has been published elsewhere (Lozano et al., 2017; Thrasher et al., 2016). Passive parental consent was used, with students providing active assent. Students completed a self-administered, Spanish-language questionnaire developed from prior, validated surveys and pretested to ensure student comprehension (Thrasher et al., 2016). The survey was administered in October and November 2016. Study protocols were approved by the IRB at the Mexican National Institute of Public Health. Analyses were limited to those who reported using e-cigarettes in the prior 30 days, excluding students who had missing data for covariates (n=66). In addition, for analysis of lifetime e-cigarette use, we excluded students who answered “don’t know” to question of lifetime e-cigarette frequency use (n=l 19). Therefore, the lifetime e-cigarette frequency of use analytic sample consisted of 832 students and the e-cigarette frequency of use in the last month sample 951 middle schoolar.
2.2. Measures
Lifetime e-cigarette frequency use: Students who indicated they had used e-cigarettes in the last 30 days were asked how many times they had used e-cigarettes in their lifetime (1 time, even 1 or 2 puffs; 2-10 times, 11-20 times; 21-50 times; 51-99 times; 100 or more; don’t know) (National Institutes of Health (NIH), 2014).
E-cigarette frequency of use in the last month: Students who indicated they had used e-cigarettes in the last 30 days were asked how many days they used e-cigarettes over that time (1-2 days/month; 3-5 days/month; 6-9 days/month; 10-19 days/month; 20-29 days/month; and 30 days) (Miech et al., 2018; Lee et al., 2017).
Motivations for e-cigarette use: Students who indicated they had used e-cigarettes in the last 30 days were asked to indicate whether they had ever used e-cigarettes for any of these following reasons: “curiosity”, “to use in places where smoking is banning”, “smoking fewer cigarettes”, “to quit combustible cigarettes” and “others”. Students could select all reasons that applied to them.
2.3. Independent Variables
Use of cigarettes and other substances: Using standard questions, (IARC, 2009) student use of combustible cigarettes was categorized into: never use; trial (tried smoking, but no smoking in the past 30 days); occasional smoking (smoked 1 to 2 days cigarettes in the last month); and regular smoking (smoked on 3 or more days cigarettes in the last month). Occasional and regular smoking categories were derived from the median number of days that students smoked (18% occasional smokers and 17% regular smokers). Alcohol use was categorized as: never use; trial (tried alcohol, but no use in the past 30 days); current use (past 30 day use, but no binge drinking in this period); and current binge drinking (in a single drinking session, drank 3 or more alcoholic beverages for females or 4 or more for males in the past 30 days). (Siqueira et al., 2015). Drug use was determined by asking “Have you used marijuana in the 12 months” and “Have you used cocaine in the last 12 months?”. Those who answered “yes” to either question were classified as drug users.
E-cigarette preferences: Students reported their favorite e-cigarette flavors (i.e., “never used flavors,” “fruit,” “mint,” “tobacco,” “combined,” “others,” “no favorite flavor”). Mint flavor was the reference category because only 3% selected tobacco flavor and because fruit flavor was identified in prior research as a risk factor for e-cigarette use frequency (Morean et al., 2018). Students reported ever using e-cigarettes with different ingredients (i.e., with nicotine, without nicotine and with marijuana), with responses categorized as either with or without nicotine.
Psychosocial factors: We derived a four-level variable from measuring nicotine product use among family members (i.e., no family member uses; only cigarette smokers; only users of e-cigarettes; users of both products) and five closest friends (i.e., no friends use; only users of e-cigarettes; only cigarette smokers; users of both products). We also assessed the frequency of exposure to internet advertising for nicotine products in the last month (“no exposure,” “combustible cigarette advertising,” “e-cigarette advertising” and “both”); sensation seeking scale which has been validated for Mexican youth in prior research (4-item brief sensation seeking scale, alpha=0.80). (Stephenson et al., 2003); social acceptability of e-cigarettes (“In your opinion people disapprove or approve e-cigarette use by other people?”, with responses re-coded to “disapprove”, “neither approve nor disapprove”, “approve”, and “don’t know”); and technophilia (i.e., positive orientation toward new technology adoption), using a validated scale with questions about the number of electronic devices owned, frequency of internet activities, and the pleasure from learning new technologies, with scores divided into quartiles (Barrientos et al., 2018).
Sociodemographic variables: Questions assessed sex (female, male) and household wealth, using the Family Affluence Scale (FAS). (Boyce et al., 2006), which sums responses to questions regarding household ownership of cars (0,1, 2 or more), the number of computers in the home (0, 1, 2 or more), the student having their own room (0=no; 1=yes), and the number of vacations taken in the past year (0, 1, 2, 3 or more).
2.4. Analysis
For analyses involving consumption frequency, we derived new variables for analyzing interval-censored count data with regression models based on truncated distributions because our data include censored responses (include 1 to 2, 3 to 5, 6 to 9, 10 to 19, 20-29, and 30 days to assesses frequency of e-cigarette use in the last month and the distribution of responses is truncated (not less than 1 and not greater than 30). Bivariate and adjusted censored truncated binomial regression models were estimated for each dependent variable (number of days using e-cigarettes in the last month; lifetime frequency of e-cigarette use; number of days smoking in the last month), adjusting for school-level clustering of the data (57 middle schools). For the model of e-cigarette frequency use in the last month, sensitivity analyses were conducted using multinomial logistic regression using three response categories (0-2 days/month, 3-9 days/month and 10 days/month) Finally, the percentage of students who endorsed each reason for e-cigarette use was estimated. Then, the average frequency of past 30 days and lifetime e-cigarette use was estimated for those who endorsed each reason for use. To calculate this average, the median value for the range in each response option (i.e., “3-5 days/month”=4) was assigned to students, and the average of these median values was calculated. All data were analyzed using Stata 15.
3. Results
About 35% of students who currently used e-cigarettes were current smokers (i.e., any smoking in the last 30 days), 30% had engaged in past month binge drinking, and 25% had used illegal drugs in the last year (see Table 1). Approximately 20% of these students had a family member who used e-cigarettes and cigarettes, and most (59%) only had family members who smoked. About 60% of these students had friends who used both e-cigarettes and cigarettes, and 19% reported that society approved of e-cigarettes. Almost half of the students preferred fruit flavored e-cigarettes.
Table 1.
Characteristics of the middle school students who currently use e-cigarettes
| E-cigarette frequency use in the last month (n=951) | Lifetime e-cigarette frequency use (n=832)* | |
|---|---|---|
| Variables | % | % |
| Sex | ||
| Female | 48 | 49 |
| Male | 52 | 51 |
| FAS (1-9) (mean±SD) | 4.47 (2.18) | 4.44 (2.22) |
| Smoking status | ||
| Never | 32 | 34 |
| Trial | 31 | 31 |
| Occasional smokers | 18 | 19 |
| Regular smokers (3 days or more in the last month) | 17 | 16 |
| Alcohol use | ||
| Neither | 11 | 12 |
| Tried | 25 | 25 |
| Current | 32 | 33 |
| Binge | 31 | 29 |
| Drug use | ||
| No | 74 | 75 |
| Yes | 26 | 25 |
| Technophilia Index (mean±SD)1 | 0.004 (0.47) | −0.03 (0.47) |
| Sensation seeking (1-5) (mean±SD) | 4.11 (0.78) | 4.10 (0.78) |
| Internet advertising | ||
| Neither | 35 | 36 |
| Cigarettes | 6 | 6 |
| E-cigarette use | 33 | 33 |
| Both | 25 | 25 |
| Family use of nicotine products | ||
| Neither | 17 | 17 |
| Cigarettes | 59 | 60 |
| E-cigarette use | 2 | 3 |
| Both | 21 | 21 |
| Friends use of nicotine products | ||
| Neither | 10 | 11 |
| Cigarettes | 18 | 19 |
| E-cigarette use | 12 | 12 |
| Both | 60 | 59 |
| Societal approval | ||
| Disapprove | 22 | 22 |
| Neither approve nor disapprove | 37 | 37 |
| Approve | 19 | 19 |
| Don’t know | 23 | 22 |
| Flavor e-cigarette | ||
| Mint | 15 | 16 |
| Fruit | 45 | 46 |
| Tobacco | 3 | 3 |
| Combined | 7 | 7 |
| Do not have favorite flavor | 18 | 17 |
| Other | 11 | 11 |
| Type of liquids | ||
| Liquids without nicotine | 55 | 55 |
| Liquids with nicotine | 45 | 45 |
The mean of the technophilia measure was close to “zero” because the items were standardized to perform the factorial analyses
This subsample excluded current users who reported that they did not know the number of lifetime vaping sessions.
3.1. Lifetime Frequency of E-Cigarette Use
In adjusted models predicting frequency of lifetime e-cigarette use (see Table 2), being male (Adjusted Prevalence Ratio or APR=2.46, 95% CI 1.75-3.47), being a regular smoker (APR=1.81, 95% CI 1.03-3.19), higher family affluence (APR=1.13, 95% CI 1.03-1.24), drug use in the last year (APR=1.89, 95% CI 1.25-2.86), higher technophilia (APRquartil4 vs. quartil1=1.84, 95% CI 1.06-3.19) and, higher sensation seeking (APR=1.31 95% CI 1.02-1.68) were positively associated with lifetime frequency. Finally, compared to those who preferred mint e-cigarette flavors, preference for fruit flavors (APRfruit flavor vs mint flavor=1.90 95% CI 1.04-3.50) and combined flavors (APRcombined flavors vs. mint flavor=1.70 95% CI 1.07-2.71) were associated with greater frequency of lifetime e-cigarette use.
Table 2.
Lifetime frequency of e-cigarette use among current e-cigarette users (n=832)1 among middle school students
| Mean number of e-cigarette sessions | PR | 95% CL | APR | 95% CL | |||
|---|---|---|---|---|---|---|---|
| Sex | |||||||
| Female | 13.4 | 1.00 | 1.00 | ||||
| Male | 21.8 | 1.89*** | 1.36 | 2.62 | 2.46*** | 1.75 | 3.47 |
| FAS (1-9) (mean±SD) | 1.16 | 1.06 | 1.26 | 1.13* | 1.03 | 1.24 | |
| Smoking status | |||||||
| Never | 12.7 | 1.00 | 1.00 | ||||
| Trial | 17.8 | 1.45* | 1.00 | 2.10 | 1.16 | 0.74 | 1.82 |
| Occasional smoker | 18.1 | 1.41 | 0.90 | 2.20 | 1.16 | 0.66 | 2.03 |
| Regular smoker (3 or more days) | 27.5 | 2.65*** | 1.63 | 4.30 | 1.81* | 1.03 | 3.19 |
| Alcohol use | |||||||
| Neither | 10.2 | 1.00 | 1.00 | ||||
| Tried | 17.6 | 1.88 | 0.95 | 3.70 | 1.57 | 0.84 | 2.94 |
| Current | 15.3 | 1.55 | 0.81 | 2.93 | 1.14 | 0.60 | 2.17 |
| Binge | 23.4 | 2.71* | 1.37 | 5.34 | 1.67 | 0.87 | 3.21 |
| Drug use | |||||||
| No | 14.9 | 1.00 | 1.00 | ||||
| Yes | 27.6 | 2.49*** | 1.75 | 3.54 | 1.89** | 1.25 | 2.86 |
| Technophilia Index | |||||||
| Quartile 1 | 13.2 | 1.00 | 1.00 | ||||
| Quartile 2 | 16.8 | 1.30 | 0.83 | 2.05 | 1.19 | 0.75 | 1.91 |
| Quartile 3 | 18.2 | 1.38 | 0.87 | 2.18 | 1.14 | 0.68 | 1.90 |
| Quartile 4 | 22.7 | 1.91* | 1.14 | 3.19 | 1.84* | 1.06 | 3.19 |
| Sensation seeking (1-5) (mean±SD) | 1.42** | 1.11 | 1.82 | 1.31* | 1.02 | 1.68 | |
| Internet advertising | |||||||
| Neither | 16.2 | 1.00 | 1.00 | ||||
| Cigarettes | 22.7 | 1.44 | 0.81 | 2.56 | 1.20 | 0.62 | 2.30 |
| E-cigarette use | 14.7 | 0.89 | 0.60 | 1.30 | 0.76 | 0.51 | 1.14 |
| Both | 22.7 | 1.47 | 0.99 | 2.17 | 1.17 | 0.72 | 1.90 |
| Family use of nicotine products | |||||||
| Neither | 15.8 | 1.00 | 1.00 | ||||
| Cigarettes | 15.5 | 0.93 | 0.62 | 1.41 | 0.90 | 0.60 | 1.35 |
| E-cigarette use | 28.2 | 1.99 | 0.79 | 5.04 | 1.72 | 0.69 | 4.31 |
| Both | 24.2 | 1.67 | 0.96 | 2.93 | 1.59 | 0.91 | 2.79 |
| Friends use of nicotine products | |||||||
| Neither | 11.4 | 1.00 | 1.00 | ||||
| Cigarettes | 15.0 | 1.49 | 0.74 | 2.98 | 1.13 | 0.58 | 2.21 |
| E-cigarette use | 18.0 | 178 | 0.92 | 3.47 | 1.84 | 0.98 | 3.45 |
| Both | 19.6 | 1.90* | 1.06 | 3.42 | 1.37 | 0.74 | 2.51 |
| Societal approval | |||||||
| Disapprove | 13.9 | 1.00 | 1.00 | ||||
| Neither approve nor disapprove | 18.6 | 1.37 | 0.87 | 2.16 | 1.28 | 0.75 | 2.21 |
| Approve | 21.7 | 1.71** | 1.00 | 2.91 | 1.40 | 0.71 | 2.76 |
| Don’t know | 16.3 | 1.18 | 0.72 | 1.94 | 1.23 | 0.69 | 2.19 |
| Flavor e-cigarette | |||||||
| Mint | 10.0 | 1.00 | 1.00 | ||||
| Fruit | 20.0 | 2.41** | 1.33 | 4.39 | 1.90* | 1.04 | 3.50 |
| Tobacco | 9.1 | 0.84 | 0.40 | 1.73 | 0.64 | 0.25 | 1.64 |
| Combined | 22.7 | 2.32*** | 1.50 | 3.58 | 1.70* | 1.07 | 2.71 |
| Do not have favorite flavor | 14.2 | 1.68 | 0.81 | 3.47 | 1.49 | 0.74 | 3.01 |
| Other | 28.1 | 3.75*** | 1.96 | 7.18 | 3.12** | 1.57 | 6.24 |
| Type of liquids | |||||||
| Liquids without nicotine | 15.6 | 1.00 | |||||
| Liquids with nicotine | 20.1 | 1.36** | 1.03 | 1.80 | 1.30 | 0.96 | 1.76 |
p value=<0.05,
p value=<0.005,
p value=<0.001
Analytic sample excluded those who indicated “don’t know” to the question on lifetime frequency (n=119)
3.2. Frequency of E-Cigarette Use in the Last Month
In fully adjusted models (see Table 3), males used e-cigarettes more frequently than females in the last month (APR=1.93, 95% CI 1.53-2.44), as did students whose family members used both e-cigarettes and cigarettes (APR=1.51 95% CI 1.03-2.20). Use of drugs in the last year (APR=1.51, 95% CI 1.11-2.06) and higher technophilia (APRquartil4 vs. quartil1=1.69, 95% CI 1.23-2.31) were also positively associated with a higher frequency of use. On the other hand, occasional smokers used e-cigarettes less frequently than never smokers (APR=0.59 95% CI 0.43-0.81). Results from the multinomial model (sensitivity analyses, see Appendix 1)* were generally in the same direction as the findings reported here.
Table 3.
E-cigarette frequency of use in the last month among current e-cigarette users (n=951) among middle school students
| Mean days of use in the last month | PR | 95 CI | APR | 95 CI | |||
|---|---|---|---|---|---|---|---|
| Sex | |||||||
| Female | 4.4 | 1.00 | 1.00 | ||||
| Male | 7.3 | 1.74*** | 1.37 | 220 | 1.93** | 1.53 | 2.44 |
| FAS (1-9) (mean±SD) | 1.04 | 0.99 | 1.09 | 1.03 | 0.97 | 1.08 | |
| Smoking status | |||||||
| Never | 5.7 | 1.00 | 1.00 | ||||
| Trial | 5.5 | 0.95 | 0.75 | 1.21 | 0.82 | 0.63 | 1.07 |
| Occasional smoker | 4.7 | 0.79 | 0.56 | 1.11 | 0.59** | 0.43 | 0.81 |
| Current smoker | 8.1 | 1.58* | 1.19 | 2.11 | 1.07 | 0.75 | 1.52 |
| Alcohol use | |||||||
| Neither | 5.6 | 1.00 | 1.00 | ||||
| Tried | 5.4 | 0.95 | 0.64 | 1.42 | 0.93 | 0.62 | 1.40 |
| Current | 5.0 | 0.86 | 0.57 | 1.31 | 0.85 | 0.55 | 1.32 |
| Binge | 7.3 | 1.39 | 0.95 | 2.03 | 1.29 | 0.83 | 2.01 |
| Drug use | |||||||
| No | 5.2 | 1.00 | 1.00 | ||||
| Yes | 8.0 | 1.74*** | 1.35 | 2.24 | 1.51* | 1.11 | 2.06 |
| Technophilia Index | |||||||
| Quartile 1 | 4.8 | 1.00 | 1.00 | ||||
| Quartile 2 | 5.3 | 1.12 | 077 | 1.61 | 1.15 | 0.80 | 1.63 |
| Quartile 3 | 6.0 | 1.32 | 0.95 | 1.84 | 1.32 | 0.93 | 1.88 |
| Quartile 4 | 7.4 | 1.73** | 1.23 | 2.2 | 1.69** | 1.23 | 2.31 |
| Sensation seeking (1-5) (mean±SD) | 1.13 | 0.97 | 1.32 | 1.07 | 0.93 | 1.24 | |
| Internet advertising | |||||||
| Neither | 5.6 | 1.00 | 1.00 | ||||
| Cigarettes | 6.8 | 1.29 | 0.77 | 2.16 | 1.14 | 0.72 | 1.82 |
| E-cigarette use | 5.7 | 1.04 | 0.78 | 1.38 | 0.96 | 0.72 | 1.28 |
| Both | 6.3 | 1.17 | 0.88 | 1.56 | 1.02 | 0.75 | 1.39 |
| Family use of nicotine products | |||||||
| Neither | 4.9 | 1.00 | 1.00 | ||||
| Cigarettes | 5.5 | 1.15 | 0.82 | 1.61 | 1.10 | 0.76 | 1.58 |
| E-cigarette use | 8.2 | 1.91 | 0.84 | 4.32 | 1.58 | 0.81 | 3.11 |
| Both | 7.4 | 1.65* | 1.13 | 2.40 | 1.51* | 1.03 | 2.20 |
| Friends use of nicotine products | |||||||
| Neither | 5.0 | 1.00 | 1.00 | ||||
| Cigarettes | 6.2 | 1.30 | 0.78 | 2.16 | 1.29 | 0.75 | 2.22 |
| E-cigarette use | 4.7 | 0.94 | 0.55 | 1.62 | 1.03 | 0.58 | 1.82 |
| Both | 6.2 | 1.30 | 0.84 | 2.02 | 1.29 | 0.81 | 2.06 |
| Societal approval | |||||||
| Disapprove | 5.1 | 1.00 | 1.00 | ||||
| Neither approve nor disapprove | 5.6 | 1.12 | 0.79 | 1.58 | 1.08 | 0.74 | 1.56 |
| Approve | 7.5 | 1.60* | 1.10 | 2.34 | 1.36 | 0.88 | 2.09 |
| Don’t know | 5.7 | 1.14 | 0.77 | 1.67 | 1.10 | 0.72 | 1.67 |
| Flavor e-cigarette | |||||||
| Mint | 5.3 | 1.00 | 1.00 | ||||
| Fruit | 5.4 | 1.03 | 0.72 | 1.48 | 0.92 | 0.64 | 1.33 |
| Tobacco | 7.5 | 1.54 | 0.88 | 2.71 | 1.36 | 0.75 | 2.45 |
| Combined | 7.4 | 1.52 | 0.94 | 2.46 | 1.33 | 0.81 | 2.21 |
| Do not have favorite flavor | 5.8 | 1.11 | 0.72 | 1.71 | 1.07 | 0.70 | 1.63 |
| Other | 7.4 | 1.52 | 0.91 | 2.56 | 1.41 | 0.85 | 2.34 |
| Type of liquids | |||||||
| Liquids without nicotine | 5.9 | 1.00 | 1.00 | ||||
| Liquids with nicotine | 5.9 | 1.09 | 0.91 | 1.32 | 1.00 | 0.81 | 1.23 |
p value=<0.05,
p value=<0.005,
p value=<0.001
3.3. Motivations for E-Cigarette Use
The most common reason for using e-cigarettes (Table 4) was curiosity (about 70.0%), with those who endorsed this reason using an average of 4.6 days in the prior month and 13.4 lifetime e-cigarette use sessions. Fewer students reported using e-cigarettes in places where cigarettes were banned (9.6%), to smoke fewer cigarettes (16.6%), and to quit smoking (7.5%). However, students who reported these reasons used e-cigarettes more frequently in the last month (9.5, 7.7 and 10.5 days, respectively) and over their lifetimes (28.3, 25.0, and 36.4 sessions, respectively) relative to those who were motivated by curiosity.
Table 4. Reasons for use* and frequency of use** among middle school students who currently use e-cigarettes.
*students could choose all responses that applied.
**mean frequency of use was estimated by using the midpoint for each response option.
| % | Days or e-cigarette use Mean (95% CI |
Lifetime number of e-cigarette sessions1 Mean (95% CI) |
|
|---|---|---|---|
| Curiosity | 68.1 | 4.6 (4.1-5.2) | 13.4 (10.2-15.4) |
| To use it in places where smoking is banned | 9.6 | 9.5 (7.4-11.6) | 28.3 (20.1-36.7) |
| To smoke fewer cigarettes | 16.6 | 7.7 (6.3-9.1) | 25.0 (19.6-30.6) |
| To quit smoking cigarettes | 7.5 | 10.5 (8.0-12.9) | 36.4 (27.0-45.9) |
| Other reasons | 14.1 | 10.4 (8.5-12.2) | 30.0 (22.6-30.0) |
Analytic sample excluded those who indicated “don’t know” to the question on lifetime frequency (n=119)
4. Discussion
The results from this study of Mexican middle schoolers were somewhat consistent with prior studies. Being a regular current smoker was unassociated with frequency of use in the last month, which is not consistent with previous studies (Lee et al., 2017; McCabe et al., 2017); still, it was associated with higher lifetime frequency of e-cigarette use, perhaps because lifetime use allowed for more meaningful variation in our relatively young sample. Interestingly, occasional smokers used e-cigarette less frequently in the last month compared to never smokers. This may be because never smokers are using e-cigarettes instead of cigarettes that they would have smoked had e-cigarettes not been available. Indeed, the introduction of e-cigarettes into the US market appears associated with declining prevalence of cigarette use amongst youth (Levy et al., 2018). However, it is also possible that the use of e-cigarettes among never smokers could lead to experimenting with cigarettes or being regular cigarette users in the future (Best et al, 2018; Conner et al, 2018; Wills et al 2017), although the strength of the association between exclusive e-cigarette use and subsequent smoking is substantially weaker in Mexico than found in other countries (Lozano et al., 2017). To better examine this issue, studies are needed with longer follow up and surveillance is needed of population-level trends in the prevalence of cigarette and e-cigarette.
Compared to students who had not used drugs in the last year, those who used them also used e-cigarettes more frequently, whether assessed for the last month or in their lifetimes, which is consistent with prior research (Dunbar et al., 2017). By contrast with this research, however, alcohol use was unassociated with a higher frequency of e-cigarette use. These findings suggest that e-cigarette users in Mexico are a relatively heterogeneous group.
Unlike prior studies (Morean et al., 2018; Vogel et al., 2018; Goldenson et al., 2017), we did not find any associations between the use of e-cigarettes with nicotine and higher frequency of use (in the last month and lifetime). This may be because we only queried ever rather than current use of e-cigarettes with nicotine. It is also possible that study participants incorrectly identified the nicotine content of e-liquids they used, as many adolescents hold incorrect knowledge of e-cigarette ingredients (Buettner-Schmidt et al., 2016) and some e-cigarettes are incorrectly labeled as not containing nicotine when they do (Gorukanti et al., 2017). This phenomenon may be amplified in a country where e-cigarette packaging and labeling are unregulated precisely because their sales are illegal.
Students who preferred e-cigarettes with fruit flavors or combined flavors were more frequent lifetime, but not current, e-cigarette users than students who preferred mint flavors. Similarly, US adolescents who preferred a greater number of flavors and fruit flavors consumed e-cigarettes more frequently in the last month (Morean et al., 2018). Furthermore, 45% of current e-cigarette users in our sample preferred e-cigarettes with fruit flavors, which indicates that sweet flavors appeal to Mexican youth. This suggests the importance of regulations to limit e-cigarette flavors in order to reduce e-cigarette appeal among youth (Morean et al., 2018; FDA, 2016).
Reporting higher levels of technophilia were associated with a higher frequency of e-cigarette use (in the last month and lifetime). This finding contrasts somewhat with previous studies in Mexico, in which stronger technophilia was associated with trial of e-cigarettes, but not with current use (Barrientos et al., 2018; Thrasher et al., 2016). However, it appears that, among current e-cigarette users, higher levels of technophilia are associated with greater frequency of use, as would be predicted by the theory of technophilia. (Barrientos et al., 2018; Martínez–Córcoles et al., 2017; Emelin et al., 2013). This theory may best characterize the intensity of engagement with new electronic devices.
Having a family member who used both (e-cigarettes and cigarettes) was associated with higher frequency of e-cigarette use (in the last month). Having family members who use e-cigarettes may have provided access to e-cigarettes, especially since e-cigarette sales are banned in Mexico. Even in the US, where e-cigarettes are legal and widely available, receipt of one’s first e-cigarette from a family member was associated with more frequent use (Vogel et al., 2018). Future longitudinal research should assess the independent effects of perceived peer, parental, and societal approval of e-cigarettes on e-cigarette frequency of use.
Consistent with some prior research study (Morean et al., 2018), including nationally representative surveys in Mexico (Zavala et al., 2018), males were more likely than females to use e-cigarettes with higher frequency in the last month and over their lifetime. However, among adults who smoke in Mexico, females are more likely than males to use e-cigarettes (Zavala et al., 2018). Research is needed to better understand the reasons for gender differences in the patterns of e-cigarette consumption, including transitions between cigarettes and e-cigarettes.
Consistent with previous studies (Lee et al., 2017; Patrick et al., 2016), curiosity was the most common reason for using e-cigarettes in our study. However, those who reported this reason used e-cigarettes less frequently than those who reported using e-cigarettes for other reasons (i.e., to smoke in places where smoking is banned, to smoke less, to quit combustible cigarettes). It is important to note that relatively few students used an e-cigarette to help them quit smoking (7.5%). Further longitudinal research is sorely needed to more closely examine whether youth who would have otherwise become smokers are using e-cigarettes instead of cigarettes, as has been suggested by some recent research in the US (Levy et al 2018).
This study has several limitations, including the cross-sectional nature of the data. Reverse causality could account for some of the results found for time-varying covariates, such as drug use. To help minimize this possibility, only variables with a theoretical or empirical justification were included in the models. Future studies are needed to evaluate these associations using longitudinal samples, where changes in the frequency of different product use and transitions between products can also be evaluated. Also, different time frames were used when querying illegal drugs (past 12 months) than alcohol and tobacco products (past 30 days). Ideally, all behaviors would be queried with the same time frame. However, adolescent use of illegal drugs is quite low in Mexico, including use in the last year (3.1%) (Villatoro-Velázquez et al., 2017). Given the young age of our sample and concerns about adequate sample size for meaningful analyses, we believe our approach is justifiable for the Mexican context. Additionally, students were asked about ever using e-cigarettes with nicotine instead of current use, which may be more relevant for understanding frequency of use and its consequences. Nevertheless, asking ever use of e-cigarettes with nicotine is meaningful among middle school adolescents like those in our sample, because this may signify progression to heavier use in the future.
Measurement of the lifetime frequency of e-cigarette use may be biased; however, we aimed to reduce this potential bias by excluding from the analytic sample the students who indicated that they don’t know. We also limited our analytic sample to current e-cigarette users, who may be more likely than past users to provide more reliable responses about lifetime use. Still, it is unclear how any recall bias may have influenced our results. Finally, the results are not generalizable to the Mexican population as the sample was only representative of public middle school students in the three largest cities in Mexico. However, three-quarters of Mexicans live in urban areas (CONAPO, 2014), and our large sample allows for inferences regarding the main urban settings in Mexico.
Despite these limitations, this study provides valuable insights because it is the first of its type in Latin America, and the only study we know of to examine this issue in a country that bans e-cigarettes. Also, this study uses a novel statistical approach which allowed us to maintain the variation in the original response options that would have otherwise been lost if we had collapsed response categories. Results from the models were qualitatively and quantitatively consistent with the multinomial models that we conducted as sensitivity analyses, although our approach allowed for greater parsimony because we modeled variation across all response options instead of comparing more than two dependent variable categories. Furthermore, we evaluated most previously studied risk factors for e-cigarette use frequency, so omitted variable bias is unlikely to seriously threaten our conclusions.
4.1. Conclusions
Overall, our study shows that some correlates for e-cigarette frequency use, both across one’s lifetime and in the last month, are different among Mexican adolescents compared to youth in other countries. In particular, we found a novel association between higher technophilia and greater frequency of e-cigarette use, which should be subject to future studies, including different populations and countries. Also, the use of e-cigarettes with nicotine was unassociated with use frequency, which contrasts with prior studies (Vogel et al., 2018; Goldenson et al., 2017;). On the other hand, some risk factors appear common with other studies (i.e., being male (Morean et al., 2018); drug use (Dunbar et al., 2017); having a family member who uses e-cigarettes and cigarettes (Vogel et al., 2018)), and are likely to be important determinants across sociocultural and regulatory contexts.
Supplementary Material
Highlights.
Evaluates e-cigarette frequency use among students in a country that bans them
being a current smoker was unassociated with past month frequency of e-cigarette use
We found an association between the novel measure of technophilia with frequency of e-cigarette use
Students who use e-cigarettes with fruit flavors were more frequent e-cigarette users
The appeal of sweet flavors, suggests the relevance of regulating e-cigarette contents
Acknowledgments
Role of Funding Source
This research was supported by grants from the Fogarty International Center and the National Cancer Institute of the United States’ National Institute of Health (R01 TW009274 & R01 TW010652). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Footnotes
Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Supplementary material can be found by accessing the online version of this paper.
Conflict of Interest
No conflict declared
References
- Adkison SE, O’Connor RJ, Bansal-Travers M, Hyland A, Borland R, Yong H-H, Fong GT (2013). Electronic nicotine delivery systems: international tobacco control four-country survey. American Journal Of Preventive Medicine, 44(3), 207–215. 10.1016/j.amepre.2012.10.018 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Barrientos-Gutierrez I, Lozano P, Arillo-Santillan E, Morello P, Mejia R, & Thrasher JF (2018). “Technophilia”: A new risk factor for electronic cigarette use among early adolescents? Addictive Behaviors. 10.1016/j.addbeh.2018.09.004 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Barrington-Trimis JL, Urman R, Berhane K, Unger JB, Cruz TB, Pentz MA, McConnell R (2016). E-Cigarettes and Future Cigarette Use. Pediatrics, 138(1). 10.1542/peds.2016-0379 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Best C, Haseen F, Currie D, Ozakinci G, MacKintosh AM, Stead M, … & Haw S (2018). Relationship between trying an electronic cigarette and subsequent cigarette experimentation in Scottish adolescents: a cohort study. Tobacco Control, 27, 373–383. doi: 10.1136/tobaccocontrol-2017-053691. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bold KW, Morean ME, Kong G, Simon P, Camenga DR, Cavallo DA, & Krishnan-Sarin S (2017). Early age of e-cigarette use onset mediates the association between impulsivity and e-cigarette use frequency in youth. Drug And Alcohol Dependence, 181, 146–151. 10.1016/j.drugalcdep.2017.09.025. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Boyce W, Torsheim T, Currie C, Zambon A, (2006). The family affluence scale as a measure of national wealth: validation of an adolescent self-report measure. Social indicators research. 78, 473–487. [Google Scholar]
- Buettner-Schmidt K, Miller DR, & Balasubramanian N (2016). Electronic Cigarette Refill Liquids: Child-Resistant Packaging, Nicotine Content, and Sales to Minors. Journal Of Pediatric Nursing, 31(4), 373–379. 10.1016/j.pedn.2016.03.019 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cámara de Diputados del H. Congreso de la Union. (2008). Ley general para el control del tabaco. Diario Oficial de la Federación 15-06-2018. Retrieved from http://www.diputados.gob.mx/LeyesBiblio/pdf/LGCT_150618.pdf
- CONAPO., 2014 México en cifras. (2014) Retrieved from http://www.conapo.gob.mx/en/CONAPO/Mexico_en_cifras
- Conner M, Grogan S, Simms-Ellis R, Flett K, Sykes-Muskett B, Cowap L,… & Siddiqi K (2018). Do electronic cigarettes increase cigarette smoking in UK adolescents? Evidence from a 12-month prospective study. Tobacco Control, 27, 365–372. doi: 10.1136/tobaccocontrol-2016-053539 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Czoli CD, Hammond D, & White CM (2014). Electronic cigarettes in Canada: prevalence of use and perceptions among youth and young adults. Canadian Journal Of Public Health = Revue Canadienne De Sante Publique, 105(2), e97–el02. Retrieved from http://search.ebscohost.com/login.aspx?direct=true&db=mdc&AN=24886856&site=ehost-live [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dunbar MS, Tucker JS, Ewing BA, Pedersen ER, Miles JNV, Shih RA, & D’Amico EJ (2017). Frequency of E-cigarette Use, Health Status, and Risk and Protective Health Behaviors in Adolescents. Journal Of Addiction Medicine, 11(1), 55–62. 10.1097/ADM.0000000000000272 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Emelin V, Thhostov A, Rasskazova E (2013). Excessive Use of Internet Mobile Phones and Computers: the Role of Technology-related Changes in Needs and Psychological Boundaries. Social and Behavioral Sciences 86 ( 2013 ) 530–535 doi: 10.1016/j.sbspro.2013.08.609 [DOI] [Google Scholar]
- Glasser AM, Collins L, Pearson JL, Abudayyeh H, Niaura RS, Abrams DB, & Villanti AC (2017). Overview of Electronic Nicotine Delivery Systems: A Systematic Review. American Journal Of Preventive Medicine, 52(2), e33–e66. 10.1016/j.amepre.2016.10.036 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Goldenson NI, Leventhal AM, Stone MD, McConnell RS, & Barrington-Trimis JL (2017). Associations of Electronic Cigarette Nicotine Concentration With Subsequent Cigarette Smoking and Vaping Levels in Adolescents. JAMA Pediatrics, 171(12), 1192–1199. 10.1001/jamapediatrics.2017.3209 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gorukanti A, Delucchi K, Ling P, Fisher-Travis R, & Halpern-Felsher B (2017). Adolescents’ attitudes towards e-cigarette ingredients, safety, addictive properties, social norms, and regulation. Preventive Medicine, 94, 65–71. 10.1016/j.ypmed.2016.10.019 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Griffiths MD, (1995) Technological addictions. Clinical Psychology Forum, 76, pp. 14–19 [Google Scholar]
- International Agency for Research on Cancer. IARC (2009) Handbooks of Cancer Prevention: Tobacco Control Volume 12 Methods for Evaluating Tobacco Control Policies. Lyon, France. [Google Scholar]
- Lee JA, Lee S, & Cho H-J (2017). The Relation between Frequency of E-Cigarette Use and Frequency and Intensity of Cigarette Smoking among South Korean Adolescents. International Journal Of Environmental Research And Public Health, 14(3). 10.3390/ijerph14030305 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Leventhal AM, Strong DR, Kirkpatrick MG, Unger JB, Sussman S, Riggs NR, Audrain-McGovern J (2015). Association of Electronic Cigarette Use With Initiation of Combustible Tobacco Product Smoking in Early Adolescence. JAMA, 314(7), 700–707. 10.1001/jama.2015.8950 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Levy DT, Warner KE, Cummings KM, Hammond D, Kuo C, Fong GT, … Borland R (2018). Examining the relationship of vaping to smoking initiation among US youth and young adults: a reality check. Tobacco Control. 10.1136/tobaccocontrol-2018-054446 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lozano P, Barrientos-Gutierrez I, Arillo-Santillan E, Morello P, Mejia R, Sargent JD, & Thrasher JF (2017). A longitudinal study of electronic cigarette use and onset of conventional cigarette smoking and marijuana use among Mexican adolescents. Drug And Alcohol Dependence, 180, 427–430. 10.1016/j.drugalcdep.2017.09.001 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Martínez–Córcoles M, Teichmann M, Murdvee M (2017). Assessing technophobia and technophilia: Development and validation of a questionnaire. Technology in Society. 51 10.1016/j.techsoc.2017.09.007 [DOI] [Google Scholar]
- McCabe SE, Veliz P, McCabe VV, & Boyd CJ (2017). Smoking behaviors and intentions among current e-cigarette users, cigarette smokers, and dual users: A national survey of U.S. high school seniors. Preventive Medicine, 99, 228–235. 10.1016/j.ypmed.2017.02.025. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Miech RA, Johnston LD, O’Malley PM , Bachman JG, Schulenberg JE , Patrick ME (2018). Monitoring the Future National Survey Results on Drug Use, 1975-2017: Volume I, Secondary School Students Institute for Social Research, The University of Michigan, Ann Arbor [Google Scholar]
- Miech R, Patrick ME, O’Malley PM, & Johnston LD (2017). What are kids vaping? Results from a national survey of US adolescents. Tobacco Control, 26(4), 386–391. 10.1136/tobaccocontrol-2016-053014 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Morean ME, Butler ER, Bold KW, Kong G, Camenga DR, Cavallo DA, … Krishnan-Sarin S (2018). Preferring more e-cigarette flavors is associated with e-cigarette use frequency among adolescents but not adults. Plos One, 13(1), e0189015 10.1371/journal.pone.0189015. [DOI] [PMC free article] [PubMed] [Google Scholar]
- National Institutes of Health (NIH) (2014). Population assessment of tobacco and health (PATH) study. Retrieved from: http://pathstudyinfo.nih.gov/UI/Home.aspx
- Neff LJ, Arrazola RA, Caraballo RS, Corey CG, Cox S, King BA, Choiniere CJ, Husten CG. Frequency of Tobacco Use Among Middle and High School Students—United States, 2014. MMWR Morb Mortal Wkly Rep. 2015. October 2;64(38): 1061–5. doi: 10.15585/mmwr.mm6438a1 [DOI] [PubMed] [Google Scholar]
- Patrick ME, Miech RA, Carlier C, O’Malley PM, Johnston LD, & Schulenberg JE (2016). Self-reported reasons for vaping among 8th, 10th, and 12th graders in the US: Nationally-representative results. Drug And Alcohol Dependence, 165, 275–278. 10.1016/j.drugalcdep.2016.05.017. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Primack BA, Soneji S, Stoolmiller M, Fine MJ, & Sargent JD (2015). Progression to Traditional Cigarette Smoking After Electronic Cigarette Use Among US Adolescents and Young Adults. JAMA Pediatrics, 169(11), 1018–1023. 10.1001/jamapediatrics.2015.1742. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ronit P (2011). Technophilia: A new model for technology adoption. UK academy for information systems conference proceedings 2011 Retrieved from http://aisel.aisnet.org/cgi/viewcontent.cgi?article=1040&context=ukais2011. [Google Scholar]
- Siqueira L, Smith VC (2015) COMMITTEE ON SUBSTANCE ABUSE. Binge Drinking. Pediatrics. 136(3):e718–26. [DOI] [PubMed] [Google Scholar]
- Stephenson MT, Hoyle RH, Palmgreen P, & Slater MD (2003). Brief measures of sensation seeking for screening and large-scale surveys. Drug And Alcohol Dependence, 72(3), 279–286. Retrieved from http://search.ebscohost.com/login.aspx?direct=true&db=mdc&AN=14643945&site=ehost-live [DOI] [PubMed] [Google Scholar]
- Thrasher JF, Abad-Vivero EN, Barrientos-Gutíerrez I, Pérez-Hernández R, Reynales-Shigematsu LM, Mejía R, … Sargent JD (2016). Prevalence and Correlates of E-Cigarette Perceptions and Trial Among Early Adolescents in Mexico. The Journal Of Adolescent Health: Official Publication Of The Society For Adolescent Medicine, 58(3), 358–365. 10.1016/j.jadohealth.2015.11.008 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tsai J, Walton K, Coleman BN, Sharapova SR, Johnson SE, Kennedy SM, & Caraballo RS (2018). Reasons for Electronic Cigarette Use Among Middle and High School Students - National Youth Tobacco Survey, United States, 2016. MMWR. Morbidity And Mortality Weekly Report, 67(6), 196–200. 10.15585/mmwr.mm6706a5 [DOI] [PMC free article] [PubMed] [Google Scholar]
- U.S. Department of Health and Human Services. (2016) E-Cigarette Use Among Youth and Young Adults A Report of the Surgeon General. Atlanta, GA: Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, [Google Scholar]
- US Food and Drug Administration. (2016). FDA’s new regulations for e-cigarettes, cigars, and all other tobacco products. Available from: https://www.fda.gov/TobaccoProducts/Labeling/RulesRegulationsGuidance/ucm394909.htm.
- Villanti AC, Pearson JL, Glasser AM, Johnson AL, Collins LK, Niaura RS, Abrams DB. Frequency of Youth E-Cigarette and Tobacco Use Patterns in the United States: Measurement Precision Is Critical to Inform Public Health. Nicotine Tob Res. 2017. November 1;19(11):1345–1350. doi: 10.1093/ntr/ntw388. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Villatoro-Velázquez JA., Resendíz-Escobar E, Mújica-Salazar A, Bretón-Cirett M, Cañaa-Martínez V, Soto-Hernández I, et al. (2017) Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz: Instituto Nacional de Salud Pública, Comisión Nacional Contra las Adicciones, Secretaría de Salud. Encuesta Nacional de Consumo de Drogas, Alcohol y Tabaco 2016-2017: Reporte de Drogas. Ciudad de México [Google Scholar]
- Vogel EA, Ramo DE, & Rubinstein ML (2018). Prevalence and correlates of adolescents’ e-cigarette use frequency and dependence. Drug And Alcohol Dependence, 188, 109–112. 10.1016/j.drugalcdep.2018.03.051 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Warner KE (2016). Frequency of E-Cigarette Use and Cigarette Smoking by American Students in 2014. American Journal Of Preventive Medicine, 51(2), 179–184. 10.1016/j.amepre.2015.12.004 [DOI] [PubMed] [Google Scholar]
- Wills TA, Sargent JD, Gibbons FX, Pagano I, & Schweitzer R (2017). E-cigarette use is differentially related to smoking onset among lower risk adolescents. Tobacco Control, 26, 534–539. doi: 10.1136/tobaccocontrol-2016-053116 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zavala-Arciniega L, Reynales-Shigematsu LM, Lozano P, Rodríguez-Andrade MÁ, Arillo-Santillán E, Thrasher JF. Patterns of awareness and use of electronic cigarettes in Mexico, a middle-income country that bans them: Results from a 2016 national survey. Preventive Medicine. 2018;116:211–218. doi: 10.1016/j.ypmed.2018.09.018. [DOI] [PMC free article] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.