Differentiating Reasons for Young Adult E-cigarette Use Using Maximum Difference Choice Models.

INTRODUCTION: Understanding the reasons young adults use e-cigarettes (ie, vape)-and whether these motivations vary across groups-is essential for informing tobacco regulatory efforts. AIMS AND METHODS: An online panel of young adults who vape (n = 230; age = 18-30 years) completed a maximum difference discrete choice task for 15 reasons for vaping. Over 9 choice sets, participants were presented a subset of 5 reasons and selected the most and least important. Hierarchical bayesian analysis estimated the relative importance of each reason. Latent class analysis (LCA) identified groups with similarly ranked reasons for use. Multinomial regression evaluated the association between sample characteristics and class membership. RESULTS: Overall, relaxation had the highest probability of being the most important reason for use (14.8%), followed by harm reduction (13.2%), and flavors (10.3%). LCA identified five distinct classes, based on top reasons for use: 1. cessation (cigarette cessation [20.2%]; n = 80); 2. dependence (relaxation [20.5%] and unable to quit [19.2%]; n = 21); 3. relaxation (relaxation [20.6%]; n = 66); 4. socializing (socializing [22.2%]; n = 27); and 5. variable (boredom [10.5%] and acceptability [10.2%]; n = 36). Participants who were older, smoked cigarettes, or vaped more frequently were more likely to belong to the cessation class while those who were younger or more e-cigarette dependent were more likely to belong to the dependence class. CONCLUSIONS: Perceived reasons why young adults vape are highly heterogeneous and dependent on the type of user. Tobacco regulatory efforts targeting distinct types of vapers are needed to minimize the adverse public health impact of vaping without compromising appeal for smoking cessation. IMPLICATIONS: E-cigarette use remains high among young adults, with flavors, cost, and harm reduction (vs. combustible cigarettes) among the mostly commonly reported reasons for use. Yet, little is known about how relatively important these reasons are to the individual. Leveraging a maximum difference task, young adults' reasons for use were evaluated on a common interval scale and groups sharing similar reasons identified. Smoking cessation, dependence, relaxation, socialization, and boredom were respectively the most important reasons for use among five classes of vapers. E-cigarette regulatory policies should consider the distinct reasons for use as to not compromise their appeal for smoking cessation.

Secondhand nicotine vaping at home and respiratory symptoms in young adults.

RATIONALE: Despite high prevalence of e-cigarette use (vaping), little is currently known regarding the health effects of secondhand nicotine vape exposure. OBJECTIVE: To investigate whether exposure to secondhand nicotine vape exposure is associated with adverse respiratory health symptoms among young adults. METHOD: We investigated the effect of secondhand nicotine vape exposure on annually reported wheeze, bronchitic symptoms and shortness of breath in the prospective Southern California Children Health Study cohort. Data were collected from study participants (n=2097) with repeated annual surveys from 2014 (average age: 17.3 years) to 2019 (average age: 21.9). We used mixed effect logistic regression to evaluate the association between secondhand nicotine vape and respiratory symptoms after controlling for relevant confounders. RESULTS: Prevalence of secondhand nicotine vape increased from 11.7% to 15.6% during the study period in this population. Prevalence of wheeze, bronchitic symptoms and shortness of breath ranged from 12.3% to 14.9%, 19.4% to 26.0% and 16.5% to 18.1%, respectively, during the study period. Associations of secondhand nicotine vape exposure with bronchitic symptoms (OR 1.40, 95% CI 1.06 to 1.84) and shortness of breath (OR 1.53, 95% CI 1.06 to 2.21) were observed after controlling for vaping, active and passive exposure to tobacco or cannabis, and demographic characteristics (age, gender, race/ethnicity and parental education). Stronger associations were observed when analysis was restricted to participants who were neither smokers nor vapers. There were no associations with wheezing after adjustment for confounders. CONCLUSION: Secondhand nicotine vape exposure was associated with increased risk of bronchitic symptoms and shortness of breath among young adults.

Critical Challenges and Creative Solutions for Quantifying Nicotine Vaping: Qualitative Reports From Young Adults.

INTRODUCTION: Previous studies suggest that young adults who vape nicotine experience difficulty when answering survey items assessing the quantity of vaping. The current study asked young adults who vape to provide suggestions for improving the scientific measurement of vaping. AIMS AND METHODS: We conducted semi-structured qualitative interviews with 62 young adults who vape in Los Angeles, California between June 2018 and June 2019. We analyzed participants' responses to the following question: "What do you think is the best way for us to understand how much people vape?" using thematic content analysis. RESULTS: We identified two major themes: (1) challenges stemming from differences between the way researchers query about vaping and how individuals self-monitor vaping frequency, and (2) insights for future measurement of vaping. Participants reported that challenges of accurately quantifying vaping were due to inherently hard-to-answer questions (eg, puffs per day), lack of awareness of or not actively monitoring consumption of vaping products, or because vaping behaviors vary considerably between and within individuals over time, making "on-average" questions challenging. Participants discussed ideas for improving survey measures that could accurately assess vaping quantity, including querying about the type of device used, and frequency of replenishment of nicotine solutions. CONCLUSIONS: Existing vaping behavior survey measures may not accurately capture the quantity of vaping as they differ from how (or if) participants track their own vaping consumption patterns. While continued research is needed to optimally refine survey measures on vaping consumption, future measures may better align with vapers' self-monitoring by including questions on device-type and replenishment frequency. IMPLICATIONS: The present study provides insights regarding the variability that exists between vaping quantity measurements utilized by researchers and individuals who consume e-cigarettes. The qualitative data analyzed for this study support previous reports of difficulties faced by vapers when asked questions by researchers related to their vaping behavior. Furthermore, the present findings suggest the direction for the future development of accurate measurements of vaping frequency.

Tobacco and cannabis poly-substance and poly-product use trajectories across adolescence and young adulthood.

Tobacco and cannabis poly-substance and poly-product use is common in adolescents and young adults (AYAs), but few studies have examined developmental trajectories of poly-use. This study characterized the prevalence, patterns, and racial/ethnic and sex differences of developmental trajectories of use and poly-use of 8 different widely-marketed tobacco and cannabis products across adolescence and young adulthood. 3322 AYAs from Los Angeles, California completed 5 surveys from fall of 11th grade (2015) to 1-2 years post-high school (2018-2019). Self-reported past 30-day use of three tobacco (nicotine vaping, cigarette, hookah) and five cannabis (combustible, blunt, edible, vaping, dabbing) products were analyzed using parallel growth mixture modeling to identify tobacco and cannabis use and poly-use trajectories; racial/ethnic and sex differences were evaluated as correlates of trajectory membership. Five trajectories were identified: Non-Users (58.6%); Young Adult-Onset Poly-Substance/Poly-Product Users (15.8%); Decreasing Moderate Poly-Substance/Poly-Product Users (9.8%); Increasing Predominant Cannabis Poly-Product Users (8.3%); and Chronic Poly-Substance/Poly-Product Users (7.3%). Within trajectories, developmental patterns of each tobacco and cannabis product were similar. Non-Hispanic White (vs. non-NH White) participants had higher odds of belonging to the Chronic Poly-Substance/Poly-Product Users (vs. Non-Users) trajectory (aOR = 2.24[1.37,3.67]); females (vs. males) had higher odds of belonging to the Young Adult-Onset Poly-Substance/Poly-Product Users (vs. Non-Users) trajectory (aOR = 1.30[1.02-1.66]). Tobacco and cannabis poly-substance use patterns, including use of various products, appear to be a common developmental trajectory during some point in adolescence and young adulthood. The interplay of tobacco and cannabis poly-substance/poly-product use merit attention in prevention and regulatory policies to protect AYA health.

Prevalence of Young Adult Vaping, Substance Vaped, and Purchase Location Across Five Categories of Vaping Devices.

INTRODUCTION: The rapidly evolving landscape of vaping devices has complicated analyses of use patterns among youth and young adults. The current study describes the prevalence of use, substances vaped, and purchasing behaviors across five different vaping device categories. AIMS AND METHODS: Participants (n = 2505; mean age = 19.2, SD = 0.46) from a cohort in the Los Angeles area completed web-based surveys from June 2018 to October 2019. For each of four device type categories depicted via digital images (any pod-style vape, cigalike, box-mod, vape pen) and for JUUL specifically, participants reported ever and past 30-day use, substance vaped (mostly nicotine, nicotine and tetrahydrocannabinol [THC], mostly THC, neither), ownership of device (yes/no), where they obtained that device (eg, purchased themselves, from a friend), and if purchased, purchase location (eg, vape shop, online). RESULTS: Overall, 44.9% reported ever use, and 26.2% reported past 30-day use of at least one of the devices. The prevalence of past 30-day use was highest for pod-style vapes (any pod = 17.0%; JUUL = 15.1%). Among respondents who reported ever owning any device (n = 643 [25.7%]), 59.9% reported purchasing the device themselves, despite not being of legal purchasing age (15.4% of total sample); across all device types, products were most often purchased in vape shops or online. CONCLUSIONS: Across all devices, the prevalence of self-purchase of vaping devices among underage young adults in the Los Angeles area was high, and most were purchased from a vape shop or online. Tobacco control policies to prevent underage purchase of tobacco products-particularly among never smokers-are needed. IMPLICATIONS: A high proportion of underage young adults reported owning their own vaping device and having purchased it themselves from a vape shop or online. Stronger tobacco control policies and better enforcement efforts are needed to successfully prevent underage purchase of tobacco products.

Accessing Vaping Products When Underage: A Qualitative Study of Young Adults in Southern California.

INTRODUCTION: California implemented multiple strategies, such as a Tobacco 21 law and compliance checks, to reduce high rates of youth e-cigarette use. However, the prevalence of use among underage youth and young adults continues rising. Little is known about how underage individuals obtain e-cigarettes. AIMS AND METHODS: We conducted structured qualitative interviews with 61 young adult (18-25 years old) vapers in the Los Angeles, CA area between June 2018 and June 2019. Interviews were comprehensive and designed to elicit information on participants' thoughts, feelings, and experiences related to vaping. We queried participants on where and how they obtained vaping products, and participants discussed their experiences accessing products while under the legal age for sale. Directed content analysis was used to analyze interviews. RESULTS: Four concepts emerged: (1) early experimentation of e-cigarettes with peers often occurred in a school setting, (2) continued use of e-cigarettes commonly obtained through peer sales, (3) inconsistent implementation of age restrictions at in-person retailers, and (4) at online retailers. Participants had peers purchase products on their behalf and frequented in-person and online retailers with few to no age verification processes. Few participants faced challenges when purchasing products from retailers. CONCLUSIONS: The current study's findings offer insight into where and how underage individuals obtain vaping products despite restrictions to prevent them from doing so. Participant accounts of mixed ease of underage purchasing in-person and online suggest retailer education is needed, along with additional research to inform more effective policies to reduce underage access to vaping products. IMPLICATIONS: Despite legal age restrictions, e-cigarettes remain accessible to underage individuals, but specific strategies that underage youth utilize to evade legal age restrictions are largely unknown. We found that participants often accessed vaping products for the first time at school. Sales between peers were common, and participants also reported frequenting in-person retailers that inconsistently enforced age restrictions. Many participants reported little to no age verification online, though some believed online age verification measures were increasingly difficult to surpass. Knowledge of strategies underage youth utilize to access e-cigarettes can inform enforcement efforts.

Characterizing symptoms of e-cigarette dependence: a qualitative study of young adults.

BACKGROUND: While rates of e-cigarette use ('vaping') continue to potentiate concern, there is limited data on common symptoms of e-cigarette dependence among young adults who vape. This study sought to critically explore how young adults experience, manifest, and conceptualize vaping dependence symptoms in their everyday lives. METHODS: Between June 2018 and 2019, in-depth qualitative interviews were conducted with 62 young adults who use e-cigarettes (aged 18-25) and live in Southern California. We explored participants' product preferences, daily e-cigarette use patterns, vaping history, withdrawal experiences, and quit attempts or periods of cessation. We used a thematic analysis approach to interpret the transcripts. RESULTS: Young adults discussed nine dimensions of vaping dependence that were organized into two categories: 1) general nicotine dependence symptoms, and 2) unique dependence symptoms related to vaping. Nicotine dependence symptoms included cravings and urgency to use, increased use to achieve desired effects, and unsuccessful quit attempts and withdrawal. Symptoms unique to vaping dependence included greater nicotine consumption due to accessibility and lack of restrictions, habitual vaping, inability to track vaping frequency, immediate gratification and comfort, social acceptability and norms, and awareness of vaping dependency. CONCLUSIONS: In addition to nicotine dependence symptoms that have been characterized for other tobacco products, young adult e-cigarette users described unique symptoms of vaping dependence that necessitate the need for more refined measures. All dimensions of vaping dependence should be considered in discussions of policies as well as treatment and education efforts intended to protect young people from e-cigarette dependence.

Young adult perspectives on their respiratory health symptoms since vaping.

Background: Vaping among young adults (YA) has been associated with adverse respiratory health outcomes. However, key gaps remain in the literature including perspectives from YA vapers on perceived respiratory health symptoms since vaping, how they describe those symptoms and related experiences, and factors to which they attribute their respiratory health symptoms. Methods: Participants (N = 35) were 18-25 years old and self-reported as currently vaping at least once per week. In-depth, semi-structured qualitative interviews were conducted using an open-ended interview guide designed to elicit respondents' subjective vaping-related experiences. We used a thematic analysis to interpret the transcripts. Results: Participants reported adverse respiratory health symptoms (e.g., phlegm, cough, pain in lungs) that some attributed to vaping. Participants compared what is known about vaping to what is known about combustible cigarettes and described continued use of vaping products despite perceived adverse respiratory health consequences. Some participants attributed their symptoms to preexisting medical conditions (e.g., asthma) and to heavy vaping. Some described a decline in exercise-related endurance since vaping. Some participants also reported that they experienced worse respiratory symptoms when using specific brands and products (e.g., JUUL and nicotine salt formulation). Conclusions: This study provides powerful accounts from YA vapers about their experience of respiratory health symptoms that they ascribe to vaping. Future research is needed to evaluate the prevalence and severity, as well as the risk and protective factors, of adverse respiratory health symptoms associated with vaping. Addiction prevention and treatment efforts for YA vapers may help curtail adverse respiratory health impact from vaping.

Perceiving E-Cigarettes as Safe and Safer Alternative to Cigarettes Among Young Adults.

BACKGROUND: Young adults are using e-cigarettes at high rates. While the literature on the health risks associated with e-cigarettes is extensive and growing, little is known about young adults' thoughts and perceptions of the safety and harms of e-cigarettes. METHODS: We conducted one-on-one interviews with young adults aged 18 to 25 years in Los Angeles, California between June 2018 and June 2019. We interviewed and audio-recorded young adults (N = 62) who consented to the study and self-reported to have used e-cigarettes on a weekly basis or more for at least 5 months prior to study enrollment. Interviews examined participants' thoughts, feelings, and experiences related to e-cigarette use. We audio-recorded, transcribed, and coded the interviews using grounded theory analysis methods. RESULTS: Young adults often believed that e-cigarettes were safer than cigarettes and were safe to use, especially following positive vaping experiences. Young adults were skeptical of the available science on e-cigarette use and felt there was not conclusive data on the harms of e-cigarettes. In their selection of e-cigarettes over cigarettes, young adults felt they were making a conscious and healthier choice. Because young adults viewed e-cigarettes to be better for them based on their personal experiences with vaping, they felt e-cigarettes were a superior alternative to combustible tobacco. CONCLUSIONS: Young adults in our study believed that the long-term health effects of e-cigarette use are not clearly understood and were generally skeptical of the research on e-cigarette harms. Policy, education, and anti-smoking campaigns need to clarify the negative health-related consequences of e-cigarette use for young people.

Associations of alternative cannabis product use and poly-use with subsequent illicit drug use initiation during adolescence.

RATIONALE: Specific cannabis products may differentially increase risk of initiating non-cannabis illicit drug use during adolescence. OBJECTIVE: To determine whether ever- and poly-use of smoked, vaporized, edible, concentrate, or blunt cannabis products are associated with subsequent initiation of non-cannabis illicit drug use. METHODS: High school students from Los Angeles completed in-classroom surveys. The analytic sample (N = 2163; 53.9% female; 43.5% Hispanic/Latino; baseline M age = 17.1 years) included students who reported never using illicit drugs at baseline (spring, 11th grade) and provided data at follow-up (fall and spring, 12th grade). Logistic regression models assessed associations between use of smoked, vaporized, edible, concentrate, and blunt cannabis at baseline (yes/no for each product) and any non-cannabis illicit drug use initiation-including cocaine, methamphetamine, psychedelics, ecstasy, heroin, prescription opioids, or benzodiazepines-at follow-up. RESULTS: Among those who never used non-cannabis illicit drugs at baseline, ever cannabis use varied by cannabis product (smoked = 25.8%, edible = 17.5%, vaporized = 8.4%, concentrates = 3.9%, and blunts = 18.2%) and patterns of use (single product use = 8.2% and poly-product use = 21.8%). After adjustment for baseline covariates, odds of illicit drug use at follow-up were largest for baseline ever users of concentrates (aOR [95% CI] = 5.74[3.16-10.43]), followed by vaporized (aOR [95% CI] = 3.11 [2.41-4.01]), edibles (aOR [95% CI] = 3.43 [2.32-5.08]), blunts (aOR [95% CI] = 2.66[1.60-4.41]), and smoked (aOR [95% CI] = 2.57 [1.64-4.02]) cannabis. Ever use of a single product (aOR [95% CI] = 2.34 [1.26-4.34]) or 2 + products (aOR [95% CI] = 3.82 [2.73-5.35]) were also associated with greater odds of illicit drug initiation. CONCLUSIONS: For each of five different cannabis products, cannabis use was associated with greater odds of subsequent illicit drug use initiation, especially for cannabis concentrate and poly-product use.

Sociodemographic differences in young adults' recall of tobacco and cannabis marketing online and in television/film.

Young adults (YA) who report viewing pro-tobacco and cannabis marketing are at increased risk for using tobacco and cannabis. However, there is a growing diversity of tobacco and cannabis products on the market, as well as methods for marketing them. Prevalence of, and sociodemographic differences in, YA's recall of various types of tobacco and cannabis marketing is not well-characterized. Data were from a cohort of YA (mean age: 19.8) from Southern California in 2019. Respondents were asked whether they recalled having seen two types of marketing (online advertisements and portrayals of product use in TV/movies) for 5 tobacco and 3 cannabis products among never-users of tobacco (N = 954) and cannabis (N = 1,046), respectively. Sociodemographic differences in marketing recall were subsequently assessed. Among tobacco-naïve respondents, 31.3% and 49.3% recalled seeing online advertisements and tobacco use in TV/movies, respectively. Among cannabis-naïve respondents, 18.7% and 31.0% recalled seeing online advertisements and cannabis use in TV/movies, respectively. Overall, respondents recalled seeing tobacco and cannabis products on TV/movies at higher rates than seeing online advertisements, with the exception of electronic cigarettes, for which online advertisements were seen at higher rates. Women (vs. men) had higher odds of seeing tobacco (aOR = 1.9) and cannabis use in TV/movies (aOR = 1.4) and cannabis marketing online (aOR = 1.4). LGB (vs. straight) respondents had higher odds of seeing cannabis marketing online (aOR = 1.7). Efforts to regulate exposure to tobacco and cannabis marketing among young women and LGB people merit further consideration.

Young adult e-cigarette use: A latent class analysis of device and flavor use, 2018-2019.

OBJECTIVE: The myriad of e-cigarette devices and flavors used by young adults (YAs) complicates identification of the particular e-cigarette products that are associated with more frequent tobacco use and merit consideration for regulation. The current study used latent class analysis to identify distinct patterns of e-cigarette device and flavor use and evaluate their association with vaping and smoking frequency. METHODS: Cross-sectional survey data (2018-2019) from a Southern California cohort were analyzed. YAs reporting past 30-day nicotine vaping (N = 550; M age = 19.2 years) self-reported e-cigarette device type/brand and flavor. Six device (e-cig/vape pen, mech mod, box mod, JUUL, non-JUUL pod, disposable) and three flavor (tobacco, mint/menthol, sweet/fruit) indicators were included in a latent class analysis. Past 30-day nicotine vaping and cigarette smoking frequency were assessed as correlates of device and flavor class membership. RESULTS: Three classes were identified: Any Pod-Mint/Menthol or Sweet/Fruit Flavor Users (prevalance:47%); Non-JUUL-Sweet/Fruit Flavor Users (28%); and Poly-Device-Poly-Flavor Users (25%). Greater frequency of vaping and smoking were associated with higher odds of belonging to the Poly-Device-Poly-Flavor Users class vs. the Any Pod-Mint/Menthol or Sweet/Fruit Flavor Users (vaping: aOR[95%CI] = 1.36[1.16, 1.59], p < .001; smoking: aOR[95%CI] = 1.25[1.02, 1.54], p = .03) and Non-JUUL-Sweet/Fruit Flavor Users (vaping: aOR[95%CI] = 1.30[1.10, 1.53], p < .01; smoking: aOR[95%CI] = 1.42[1.07, 1.88], p = .02) classes. CONCLUSIONS: Although YAs that predominately used pod devices alongside non-tobacco flavors were most common, YAs characterized by a proclivity toward using many different devices and flavors were appreciably prevalent and smoked and vaped more frequently. Regulations targeting a wide spectrum of vaping products may be optimal in protecting YA health.

Sexual minority tobacco use disparities across adolescence and the transition to young adulthood.

INTRODUCTION: Sexual minority (SM; e.g., lesbian, gay, bisexual) youth are disproportionately more likely to use tobacco than non-SM youth, yet there exist several critical gaps in knowledge. This study assessed (a) the timing of SM tobacco use disparities (e.g., during adolescence or early adulthood), (b) whether disparities generalize across different tobacco products, and (c) whether disparities differ by sex. METHODS: Data were from a 6-year prospective cohort of diverse high school students from Southern California who were followed into early adulthood (9 waves, 2013-2019). SM (vs. non-SM) differences in past 6-month use were assessed for: any tobacco products, cigarettes, e-cigarettes, other products (e.g., hookah), and multiple products. Disparities were modeled longitudinally across adolescence (high school) and the transition to early adulthood (end of high school to post-high school). Differences were tested by sex. RESULTS: Among females, SM disparities were evident for all outcomes during both adolescence and early adulthood; no differences were observed among males. For example, SM (vs. non-SM) females had higher odds of cigarette (aOR = 4.4 [3.0-6.5]) and e-cigarette (aOR = 1.7 [1.2-2.4]) use, averaged across adolescence. The timing of disparities varied by product. For example, cigarette use disparities emerged prior to high school and persisted through adolescence and young adulthood, while e-cigarette use disparities were present in early adolescence and young adulthood only. CONCLUSIONS: Young SM females are at especially high risk for tobacco use, across various tobacco products, throughout adolescence and young adulthood. Interventions must consider differences in the timing of disparities by product type.

Trajectories of Nicotine and Cannabis Vaping and Polyuse From Adolescence to Young Adulthood.

Importance: Little is known about cannabis vaping trajectories across adolescence and young adulthood or the co-occurrence with nicotine vaping. Objective: To evaluate nicotine vaping and cannabis vaping trajectories from late adolescence to young adulthood (≥18 years of age) and the extent of polysubstance vaping. Design, Setting, and Participants: In this prospective cohort study, 5 surveys (including information on substance vaped) were completed at 10 high schools in the Los Angeles, California, metro area. Students were surveyed at 6-month intervals from fall of 11th grade (October to December 2015; wave 5) through spring of 12th grade (March to June 2017; wave 8) and again approximately 1 to 2 years after high school (October 2018 to October 2019; wave 9). Exposures: Past 30-day nicotine and cannabis vaping frequency across 5 waves. Main Outcomes and Measures: Self-reported frequency of nicotine vaping and cannabis vaping within the past 30 days across 5 time points from late adolescence to young adulthood. Trajectories were measured with these past 30-day use frequencies at each wave. Parallel growth mixture modeling estimated conditional probabilities of polysubstance vaping. Results: The analytic sample included 3322 participants with at least 1 time point of data (mean [SD] age, 16.50 [0.42] years at baseline; 1777 [53.5%] female; 1573 [47.4%] Hispanic or Latino). Growth mixture modeling identified the 5-trajectory model as optimal for both nicotine vaping and cannabis vaping. Trajectories for nicotine and cannabis vaping were similar (nonusers: 2246 [67.6%] nicotine, 2157 [64.9%] cannabis; infrequent users: 566 [17.0%] nicotine, 608 [18.3%] cannabis; moderate users: 167 [5.0%] nicotine, 233 [7.0%] cannabis; young adult-onset frequent users: 213 [6.4%] nicotine, 190 [5.7%] cannabis; adolescent-onset escalating frequent users: 131 [3.9%] nicotine, 134 [4.0%] cannabis). Males had greater odds of belonging to the adolescent-onset escalating frequent users nicotine (adjusted odds ratio, 2.88; 95% CI, 1.58-5.23; P < .01) and cannabis (adjusted odds ratio, 1.95; 95% CI,1.03-3.66; P < .05) vaping trajectories compared with nonusers. Polysubstance vaping was common, with those in trajectories reflecting more frequent nicotine vaping (adolescent-onset escalating frequent users and young adult-onset frequent users) having a high probability of membership (85% and 93%, respectively) in a cannabis-use trajectory. Conclusions and Relevance: In this cohort study, the prevalence and type of nicotine vaping and cannabis vaping developmental trajectories from late adolescence to young adulthood were similar. Polysubstance vaping was common from late adolescence to young adulthood, particularly among those reporting more frequent vaping use. The findings suggest that public health policy and clinical interventions should address polysubstance vaping in both adolescence and young adulthood.

Trends in the Age of Cigarette Smoking Initiation Among Young Adults in the US From 2002 to 2018.

Importance: Success in reducing the prevalence of adolescent smoking could reflect complete prevention of smoking initiation or a shift in the age of cigarette smoking initiation from adolescence into early adulthood. Objective: To assess trends in early adult (ages 18-23 years) vs adolescent (age <18 years) cigarette smoking initiation and transition to daily cigarette smoking from 2002 to 2018. Design, Setting, and Participants: Ages at initiation of smoking and the transition to daily smoking were ascertained from the National Survey on Drug Use and Health (2002-2018), an annual, population-based, repeated cross-sectional study representative of the US population. This cross-sectional analysis was restricted to young adults who completed the survey at ages 22 to 23 years during survey years 2002 to 2018 to limit potential age-related recall bias. Retrospectively collected age of cigarette smoking initiation was assessed among ever cigarette smokers; age of transition to daily smoking was assessed among ever daily cigarette smokers. Data analysis was performed from June 2019 to July 2020. Exposures: Calendar year of survey (2002 to 2018). Main Outcomes and Measures: The main outcomes were population-weighted cigarette smoking prevalence and cigarette smoking initiation and transition to daily smoking in adolescence (age <18 years) vs early adulthood (ages 18-23 years). Results: Among 71 756 young adults aged 22 to 23 years (38 226 women [50.5%]), ever cigarette smoking prevalence decreased from a population-weighted estimate of 74.6% (95% CI, 73.1%-75.9%) in 2002 to 51.4% (95% CI, 49.3%-53.5%) in 2018 (P < .001). Daily smoking prevalence rates similarly decreased from 41.1% (95% CI, 39.1%-43.1%) in 2002 to 20.2% (95% CI, 18.6%-21.8%) in 2018 (P < .001). However, among 48 015 ever smokers, the proportion initiating smoking in early adulthood (ages 18-23 years) increased over this time, from 20.6% (95% CI, 18.5%-22.8%) in 2002 to 42.6% (95% CI, 39.6%-45.7%) in 2018 (P < .001). Similarly, among 24 490 daily cigarette smokers, the proportion who transitioned to daily smoking in early adulthood increased from 38.7% (95% CI, 35.9%-41.6%) in 2002 to 55.9% (95% CI, 52.0%-59.8%) in 2018 (P < .001). Conclusions and Relevance: A substantial proportion of beginning smokers and most new daily smokers are now young adults, reflecting a shift from adolescence to early adulthood, a population segment once considered beyond the critical risk period for cigarette smoking onset. Expanding the long-standing emphasis on adolescent surveillance and prevention in adolescence to include the young adult population is warranted.

Assessment of Nicotine and Cannabis Vaping and Respiratory Symptoms in Young Adults.

Importance: Rates of e-cigarette use (ie, nicotine vaping) and cannabis vaping continue to increase among youth and young adults. However, the association of nicotine and cannabis vaping with independent respiratory health outcomes has not been well studied. Objective: To investigate associations of nicotine and cannabis vaping with bronchitic symptoms, wheeze, and shortness of breath. Design, Setting, and Participants: Cross-sectional survey data on self-reported lifetime, 6-month, and 30-day vaping from 2553 young adults recruited from high schools in Southern California were collected from June 2018 to October 2019. Of these participants, 94% provided data for shortness of breath and wheeze, and 86% provided data for chronic bronchitis. Main Outcomes and Measures: Self-reported nicotine and cannabis vaping were measured on a Likert-type scale using the following responses: (1) never used, (2) lifetime but no past 6-month use, (3) past 6-month use but no use in the past 30 days, (4) use on 1 or 2 of the past 30 days, and (5) use on 3 or more of the past 30 days. Three respiratory health outcomes were assessed separately on the basis of self-reported symptoms: bronchitic symptoms in the previous 12 months (ie, daily cough for 3 months in a row, congestion or phlegm other than with a cold, and/or bronchitis), wheeze in the previous 12 months, and shortness of breath when hurrying on level ground or walking up a slight hill. Results: Of 2553 participants in the analytic sample (mean [SD] age, 19.3 [0.79] years; 1477 [57.9%] female individuals), 1095 of 2553 young adults (42.9%) reported vaping nicotine and 939 of 2553 (38.4%) reported vaping cannabis. Compared with those who never vaped cannabis, individuals who vaped cannabis in their lifetime but not in the past 60 months (204 of 2553 [8.4%]; adjusted odds ratio [aOR], 1.83 [95% CI, 1.08-3.10]), in the past 6 months but not in the last 30 days (490 of 2443 [20.1%]; aOR, 1.58 [95% CI, 1.02-2.46]), 1-2 days in the past 30 days (90 of 2443 [3.7%]; aOR, 2.83 [95% CI, 1.46-5.50]), and 3 or more days in the past 30 days (155 of 2443 [6.3%]; aOR, 2.14 [95% CI, 1.16-3.92]) had significantly higher odds of chronic bronchitic symptoms after adjusting for nicotine vaping, cigarette smoking, cannabis smoking, and sociodemographic characteristics. Cannabis vaping 3 or more times in the last 30 days was also associated with increased odds of wheeze (aOR, 2.27 [95% CI, 1.17-4.37]). Associations of cannabis vaping with shortness of breath and nicotine vaping with any respiratory health outcome were not statistically significant in fully adjusted models. Conclusions and Relevance: Findings of this cross-sectional study suggest that cannabis vaping is associated with increased risk of bronchitic symptoms and wheeze in young adults. Further research is needed to understand the temporality of the association and the mechanisms underlying the difference between nicotine and cannabis vaping in the risk of bronchitic symptoms and wheeze.

Contemporary Patterns of Marijuana Use and Attitudes Among High School Seniors: 2010-2016.

PURPOSE: The goal of this study was to examine changes in contemporary patterns of marijuana use and attitudes over time. Given shifts in state-by-state marijuana legislation, there is a reason to believe that the patterns of high school seniors' marijuana use behavior and attitudes about use have changed from 2010 to 2016. METHODS: Data are from high school seniors in the 2010-2016 waves of Monitoring the Future, a nationally representative, cross-sectional survey in the United States. Latent class analysis was used to determine underlying patterns of marijuana use and related attitudes. Differences in latent class membership were examined across years, and gender and race/ethnicity were also examined. RESULTS: Five latent classes were identified: Intolerant Nonusers (49% of the sample), Tolerant Nonusers (12%), Disapproving Users (7%), Experimenters (6%), and Marijuana Enthusiasts (26%). Class prevalences remained relatively stable from 2010 to 2013; beginning in 2014 a significant decrease in prevalence was observed for Intolerant Nonusers and significant increases in prevalence were observed for Tolerant Nonusers and Marijuana Enthusiasts. Membership in the Marijuana Enthusiasts class was consistently more likely for males; Hispanic and black adolescents were more likely to be Disapproving Users. CONCLUSIONS: Contemporary patterns of marijuana use and attitudes have remained consistent over time, however, significant shifts in class prevalence emerged in 2014. Findings also suggest that a substantial subgroup of adolescents would benefit from prevention and intervention efforts targeting marijuana use and attitudes.

Nicotine dependence predicts cannabis use disorder symptoms among adolescents and young adults.

PURPOSE: We evaluate if cigarette smoking and/or nicotine dependence predicts cannabis use disorder symptoms among adolescent and young adult cannabis users and whether the relationships differ based on frequency of cannabis use. METHODS: Data were drawn from seven annual surveys of the NSDUH to include adolescents and young adults (age 12-21) who reported using cannabis at least once in the past 30 days (n = 21,928). Cannabis use frequency trends in the association between cigarette smoking, nicotine dependence and cannabis use disorder symptoms were assessed using Varying Coefficient Models (VCM's). RESULTS: Over half of current cannabis users also smoked cigarettes in the past 30 days (54.7% SE 0.48). Cigarette smoking in the past 30 days was associated with earlier onset of cannabis use, more frequent cannabis use and a larger number of cannabis use disorder symptoms compared to those who did not smoke cigarettes. After statistical control for socio-demographic characteristics and other substance use behaviors, nicotine dependence but not cigarette smoking quantity or frequency was positively and significantly associated with each of the cannabis use disorder symptoms as well as the total number of cannabis symptoms endorsed. Higher nicotine dependence scores were consistently associated with the cannabis use disorder symptoms across all levels of cannabis use from 1 day used (past month) to daily cannabis use, though the relationship was strongest among infrequent cannabis users. CONCLUSION: Prevention and treatment efforts should consider cigarette smoking comorbidity when addressing the increasing proportion of the US population that uses cannabis.

Emergence of electronic cigarette use in US adolescents and the link to traditional cigarette use.

BACKGROUND: Electronic cigarettes (e-cigarettes) are increasingly used by US adolescents and may be a gateway to traditional cigarette use. We examine rates of both products by age and examine differences in age-varying rates by sex and race/ethnicity. METHODS: Data are from the 2014 National Youth Tobacco Survey, a national sample of US middle and high school students (n=22.007); students ages 11-19 were included. Past 30-day e-cigarette and traditional cigarette use were examined as a function of age; sex and race/ethnicity were included as moderators. The age-varying association between e-cigarette and traditional cigarette use was also examined. RESULTS: Rates of e-cigarette use increase faster than traditional cigarette use from ages 13-16. Compared to females, males had higher rates of e-cigarette use from ages 14-17.5 and traditional cigarette use from ages 15-18. Between ages 12-14, more Hispanic adolescents used e-cigarettes compared to White or Black adolescents; after age 14 Hispanics and Whites reported similar rates, peaking at twice the rate for Blacks. Hispanic adolescents report greater traditional cigarette use versus Whites between ages 12-13, but lower rates between ages 15-18. E-cigarette use was strongly associated with traditional cigarette use, particularly during early adolescence [OR>40 before age 12]. CONCLUSIONS: Young Hispanic adolescents are at elevated risk for use of e-cigarettes and traditional cigarettes during early adolescence. During early adolescence, youth using e-cigarettes are more likely to smoke traditional cigarettes compared to youth not using e-cigarettes. The study of age-varying effects holds promise for advancing understanding of disparities in health risk behaviors.