Assessment of abuse liability and switching potential of menthol-flavored pod-based electronic nicotine delivery systems among US adults who smoke cigarettes.

BACKGROUND: Menthol-flavored electronic nicotine delivery systems (ENDS) are a focus of public health and regulatory policy considerations. The abuse liability of five menthol-flavored pod-based ENDS was compared to combustible cigarettes, and switching potential of ENDS was also evaluated. METHODS: 215 US adults who smoke cigarettes (34.4% female; mean age[SD]=29.60[8.75]; 40.9% non-Hispanic White; mean cigarettes/day[SD]=12.04[8.52]) completed a randomized 6-arm within-person cross-over product-use study. Participants used five pod-based menthol-flavored ENDS (JUUL2 Polar Menthol 1.5%, JUUL2 Prototype Fresh Menthol 3.0%, JUUL Menthol 5.0%, Vuse Alto Menthol 5.0%, NJOY Ace Menthol 5.0%) and their usual brand (UB) cigarette for 20minutes ad libitum. After each product use, subjective reinforcing effects relevant to abuse liability and associated with switching away from cigarettes (e.g., satisfaction, product liking) were assessed. RESULTS: All ENDS products were rated substantially and statistically significantly lower than UB cigarette on measures of subjective reinforcing effects (ps<0.001). Satisfying effects of JUUL2 1.5% were rated significantly higher than other ENDS products. JUUL2 Prototype 3.0% and Vuse Alto 5.0% did not significantly differ (ps>0.05), and both were rated significantly higher than JUUL 5.0% and NJOY Ace 5.0% (ps<0.05). Differences in subjective responses to study products did not significantly differ by preference for menthol cigarettes or by current ENDS use. CONCLUSIONS: Abuse liability of all menthol-flavored ENDS in this study was substantially lower than combustible cigarettes. Abuse liability of JUUL2 1.5% was within the range of currently marketed pod-based menthol-flavored ENDS products. JUUL2 1.5% likely has high potential for facilitating switching among US adults who smoke.

Methodological considerations when assessing symptoms of nicotine dependence by cigarette and e-cigarette use behavior and brand.

Letter to the Editor re: Adjei et al., 2024. Symptoms of nicotine dependence by e-cigarette and cigarette use behavior and brand: A population-based, nationally representative cross-sectional study. Drug and Alcohol Dependence 255, 111059 concerning issues of context, citations, non-psychometrically validated dependence items, and disclosure transparency.

Switching Away From Smoking and Reduction in Cigarette Consumption among US Adult Purchasers of the JUUL System across 24 Months Including Diverse Subpopulations Disproportionately Affected by Cigarette Smoking.

OBJECTIVES: Electronic nicotine delivery systems (ENDS) can reduce tobacco-related health risks for adults who smoke cigarettes (AWS) by facilitating complete switching away from cigarettes. However, little is known about ENDS use and switching among subpopulations that have been disproportionately affected by smoking. METHODS: AWS (age≥21 years) were recruited following their first purchase of a JUUL Starter Kit in 2018. Participants self-reported switching (no past-30-day cigarette smoking) at 1-, 2-, 3-, 6-, 9-, 12-, 15-, 18-, 21-, and 24-month follow-ups. Percent switched and percent with substantial smoking reduction (≥50% decrease in cigarettes/day among those who continued smoking) were calculated. Analyses focused on racial/ethnic minorities, persons with low income and education levels, sexual minorities, and those with mental and physical health conditions. RESULTS: Overall rates of switching away from cigarettes increased across follow-ups to 51.2% (Month-12) to 58.6% (Month-24, 87% of whom used ENDS). Among those who continued to smoke at 24 months, 45.4% reduced cigarettes/day by ≥50%. Rates of switching and substantial smoking reduction were largely similar across subgroups, with some statistically significant, but small, differences in Month-24 switching rates(e.g. education, mental/physical health conditions; switch rate range: 42~57%). CONCLUSIONS: AWS demonstrated progressively increasing switching rates over two years after purchasing JUUL products. Similar trends in switching and smoking reduction were observed across populations disproportionately affected by smoking. By facilitating switching and smoking reduction, ENDS products such as JUUL may provide an opportunity to reduce smoking-related harm among some populations disproportionately affected by smoking, potentially reducing tobacco-related health disparities. IMPLICATIONS: ENDS have the potential to benefit population health if they can replace cigarettes. This benefit must extend to populations disproportionately affected by smoking. In this real-world study, 59% of JUUL purchasers reported complete switching two years later (no past-30-day smoking, with most continuing to use ENDS). Further, 45% of those who continued to smoke reduced cigarette consumption by at least half. These rates of switching and smoking reduction were largely comparable across populations disproportionately affected by smoking (defined, e.g., by ethnicity and income). ENDS can serve as an effective harm reduction strategy to complement current efforts to reduce tobacco-related disparities.

Adult smokers' Complete Switching Away from Cigarettes at 6, 9, and 12 Months after Initially Purchasing a JUUL e-Cigarette.

Background: Electronic nicotine delivery systems (ENDS) have the potential to benefit public health if smokers completely switch from cigarettes to ENDS. Methods: A cohort of adult smokers (age ≥ 21) who purchased a JUUL Starter Kit was followed for 12 months after the initial purchase. We defined "switching" as past-30-day abstinence from smoking (even if JUUL use had stopped), and analyzed factors associated with achievement and maintenance of self-reported repeated point-prevalence switching (RPPS) at three follow-ups, i.e., no past-30-day smoking at months 6, 9, and 12. Results: RPPS was reported by 21.6% of the 12,537 evaluable smokers. Smokers with lighter smoking history and lower cigarette dependence at baseline were more likely to report RPPS. RPPS was also associated with daily use of JUUL (Month-3: OR = 2.32, 95% CI = 2.02-2.68; Month-6: OR = 1.73, 95% CI = 1.42-2.10), and with greater subjective reinforcing effects from JUUL use (assessed by the mCEQ, Month-3: OR = 1.46, 95% CI = 1.38-1.56; Month-6: OR = 1.11; 95% CI = 1.02-1.20). Even among smokers who did not meet the criteria of RPPS (i.e., who smoked at least once), 35.5% reported past 30-day point-prevalence switching on at least one follow-up, and their cigarette consumption was substantially reduced compared to baseline. Conclusions: Approximately one-fifth of adult smokers reported 30-day point-prevalence abstinence at 6, 9, and 12 months after purchasing JUUL. Greater use of JUUL and stronger subjective reinforcing effects were associated with nonsmoking, validating the potential for ENDS to substitute for smoking, with potential for positive impacts on individual and population health.

What Substances Are Adolescents Vaping? Estimating Nicotine-Specific and Cannabis-Specific Vaping from US National Youth Surveys.

BACKGROUND: Youth use of electronic cigarettes ("e-cigarettes") is an ongoing concern. Vaping is usually assumed to be of nicotine, but survey responses may also include vaping of non-nicotine substances (particularly cannabis), which can impose different risks. The current study quantifies the proportions of nicotine-specific and cannabis-specific vaping among adolescents. METHODS: Data from the Monitoring the Future (MTF) 2021 survey were analyzed with respect to the substance vaped: nicotine, cannabis, or flavoring only. Past-30-day (P30D) nicotine-specific vaping (exclusively, or also having vaped other substances) and cannabis-specific vaping were calculated. Results were also broken down by grade level, cigarette smoking history (current, former, or never), and frequency of e-cigarette use (<20 vs. 20+ days in P30D). RESULTS: Among 4706 P30D e-cigarette users, 84.2% vaped nicotine; the remaining 15.8% reported not vaping any nicotine in P30D. Cannabis vaping was reported by 48.4% of P30D vapers. Vaping both nicotine and cannabis in P30D was more common in current and former smokers than in never-smokers, and in frequent vapers (of any substance). Conversely, never-smokers were more commonly vaping cannabis but not nicotine, compared to current and former smokers. Supplementary NYTS 2022 analyses were consistent with these findings. CONCLUSIONS: A notable proportion of self-reported P30D vapers reported not vaping nicotine; nearly half vaped cannabis. Capturing the variety of substances used in vaping devices is imperative for accurate public health surveillance of both nicotine and cannabis vaping among US adolescents, considering their different respective harms and regulatory frameworks.

Comparing Adult Smokers Who Switched to JUUL versus Continuing Smokers: Biomarkers of Exposure and of Potential Harm and Respiratory Symptoms.

OBJECTIVES: Real-world evidence on exposure to harmful and potentially harmful constituents (HPHCs) and on biological effects in cigarette smokers who switch to electronic nicotine delivery systems (ENDS) can inform the health effects of switching. AIMS AND METHODS: This cross-sectional, observational study assessed adults who had smoked ≥10 cigarettes/day for ≥10 years, comparing 124 continuing cigarette smokers (Smokers) to 140 former smokers who switched to JUUL-brand ENDS exclusively for ≥6 months (Switchers). Assessments included biomarkers of exposure (BOEs) to select HPHCs, biomarkers of potential harm (BOPHs) related to smoking-related diseases, psychometric assessments of dependence on cigarettes and ENDS, respectively, and respiratory symptoms. Planned analyses compared geometric means, adjusted for demographic covariates; further analyses adjusted for additional lifestyle and smoking history covariates. RESULTS: Nicotine levels were significantly higher in Switchers (median time switched = 3 years), who were unusually heavy users of JUUL. All other BOEs, including NNAL and HPMA3 (primary endpoints), were significantly lower in Switchers than Smokers. Most BOPHs (sICAM-1 [primary], and eg, white blood cell count, MCP1, HbA1c) were significantly lower in Switchers than Smokers; HDL was significantly higher. Switchers reported significantly lower dependence on JUUL than Smokers did on cigarettes, and respiratory symptom scores were significantly lower among Switchers than Smokers. CONCLUSIONS: Compared to continuing smokers, smokers who switched to JUUL had substantially lower exposures to multiple HPHCs, favorable differences in markers of inflammation, endothelial function, oxidative stress, and cardiovascular risk, and fewer respiratory symptoms. These findings suggest that switching from cigarettes to JUUL likely reduces smokers' health risks. IMPLICATIONS: Short-term confinement studies and randomized clinical trials demonstrate that adult smokers who switch completely to ENDS experience substantial reductions in exposure to many smoking-related toxicants. This study extends those findings to longer periods of switching to JUUL-brand ENDS (almost 3 years on average) under naturalistic use conditions in real-world settings and also found that switching to JUUL resulted in favorable differences in BOPHs more proximally related to smoking-induced disease, as well as in respiratory symptoms. Smokers who switch to ENDS reduce their exposure to toxicants, likely reducing their disease risk.

Randomized trial assessing the effect of the JUUL system on switching away from cigarettes and smoking reduction among U.S. adults who smoke cigarettes.

Observational studies show high rates of switching away from cigarettes among adult purchasers of JUUL-brand electronic nicotine delivery system (ENDS); data are needed to evaluate switching with JUUL in randomized general population trials. The association of ENDS flavor availability and switching is pertinent. This study assessed switch rates and smoking reduction among participants randomized to use JUUL in a choice of flavors or tobacco-only, compared to a condition provided smoking-cessation materials. U.S. adults who smoke cigarettes (N = 837; Mage [SD] = 45.99 years [11.48]; 18.76 cigarettes/day [SD = 7.86]; 50.2% female) from an address-based representative panel were randomized to receive JUUL for 6 months (5.0% nicotine; only Virginia Tobacco [N = 285] or choice of flavors [N = 281]), or smoking-cessation materials (quit advice [QA]; N = 271). Self-reported past 30-day smoking and cigarette consumption were assessed at 1, 3, and 6 months. Repeated-measure regressions assessed differences in smoking outcomes between groups. Only 2% of participants were planning to quit smoking within 30 days. Across the 6-month intervention, participants randomized to JUUL (vs. QA) had 6.57-fold greater odds of reporting past 30-day switching (95% CI [3.72-11.63]). Participants in the JUUL (vs. QA) group smoked 27% fewer cigarettes/day versus baseline (Rate Ratio [95% CI] = 0.73 [0.68-0.77]). Over half (51.8%) of the Virginia Tobacco group used other flavors (36.7% nontobacco flavors), contaminating randomized flavor-conditions. JUUL flavor groups did not differ in smoking outcomes (p > .48). Use of JUUL products may support complete switching away from cigarettes, including among those not ready to quit smoking. Results suggest a preference for nontobacco-flavored ENDS among adults who smoke, although smoking outcomes did not differ by flavor. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Comparative risk perceptions of switching to JUUL vs. continued smoking and subsequent switching away from cigarettes: a longitudinal observational study.

BACKGROUND: Evidence indicates that electronic nicotine delivery systems (ENDS) pose lower risk than cigarettes; however, many smokers harbor misperceptions that ENDS are equally or more harmful, possibly deterring them from switching. This study examines whether comparative risk perceptions of JUUL vs. smoking are associated with subsequent switching, among smokers who recently purchased JUUL. METHODS: N = 16,996 current established smokers who recently purchased a JUUL Starter Kit were followed 6 times over 12 months. Comparative risk perceptions were assessed using both direct and indirect measures (i.e., contrasting JUUL and smoking directly in questions, and deriving from separate absolute scales). Repeated-measures logistic regression examined switching across follow-up (no smoking in past 30 days) as a function of baseline risk perceptions, adjusting for demographics and baseline smoking behavior. RESULTS: Perceiving JUUL as less harmful than smoking was associated with higher switching rates, using both direct (e.g., adjusted odds ratio [AOR] = 1.48 for "JUUL much less" vs. "more/much more harmful") and indirect (AOR = 1.07, for each 10-unit increase in fraction; AOR = 1.51 for highest (6-100) vs. lowest (0 to < 1) fraction categories) comparative risk measures (all p < 0.0001). Among the subset smoking 10 + cigarettes per day, associations between risk perceptions and switching were more pronounced (AOR = 2.51 for "JUUL much less" vs. "more/much more harmful"; AOR = 1.81 for 6-100 vs. 0 to < 1 fraction, both p < 0.0001). CONCLUSIONS: Smokers who perceive JUUL as less harmful than cigarettes have higher odds of switching. Future research should examine whether messaging which aligns comparative risk perceptions with current evidence can facilitate switching, especially among heavier smokers.

Comment on Wang et al. Consumption of JUUL vs. Other E-Cigarette Brands among U.S. E-Cigarette Users: Evidence from Wave 5 of the PATH Study. Int. J. Environ. Res. Public Health 2022, 19, 10837.

This comment is to express concern about an article by Wang et al. [...].

Switching away from smoking at 12 months among adult JUUL users varying in recent history of quit attempts made with and without smoking cessation medication.

Some smokers switch away from smoking using e-cigarettes, but guidelines recommend trying approved medications first. We analyzed switching in adult smokers using JUUL by their recent history of quit attempts and use of smoking cessation medications. Participants were 8511 adult (21+) established smokers (at baseline), in which 50.3% are daily smokers, in a longitudinal observational study who completed a survey 12 months after first purchasing a JUUL Starter Kit. At baseline, participants reported attempts to quit smoking in the prior year and use of pharmacotherapy (nicotine replacement therapy [NRT] or prescription medication) in their most recent attempt. The outcomes were switching (self-reported no past-30-day smoking) and 50%+ reductions in cigarette consumption. Multivariable analyses were adjusted for baseline covariates. Two thirds of the participants had made a quit attempt in the year before purchasing JUUL. Overall, 59% [58%, 60%] had switched at 12 months. Switching was more likely in those who had used NRT and who attempted quitting without medication versus those who used prescription medications or made no quit attempt. In adjusted multivariable analyses, only making a past-year quit attempt (vs. not) was associated with higher odds of switching (OR = 1.15 [1.04, 1.28]). Over 60% of dual users reduced cigarette consumption by ≥50%. These associations were largely similar in daily smokers. Twelve months after purchasing JUUL, almost all smokers reported either switching or reducing their smoking by 50%+, including those who had recently failed to quit smoking with approved pharmacotherapies. E-cigarettes provide an alternative route to abstinence from smoking for smokers with a history of cessation and cessation treatment failure.

Youth patterns of use of electronic nicotine delivery systems (ENDS), Population Assessment of Tobacco and Health (PATH) waves 4-5.5.

INTRODUCTION: Youth use of electronic nicotine delivery systems (ENDS) is a continuing concern, making it important to assess evolving patterns, especially as non-tobacco, non-menthol (NTM) flavors were withdrawn for pod-based (but not disposable) ENDS in February 2020. METHODS: Trends in past-30-day (P30D) ENDS use and smoking prevalence, usual device type, flavor (tobacco, mint/menthol, or fruit/sweet/other), and regular/last-used brand in PATH Waves 4 (2017), 4.5 (2018), 5 (2019), and 5.5 (2020) were examined. Shifts between 2019 and 2020 in flavor use for pods and disposables were examined. RESULTS: P30D ENDS use peaked in 2019 at 8.6 % of all youth, subsequently declining by nearly half to 4.5 % in 2020. Meanwhile, P30D cigarette smoking declined to an all-time low (1.3 %) in 2020. Within this overall decline, consumption shifted to disposable ENDS, which increased nearly 10-fold (from 5.0 % to 49.2 % of P30D ENDS users). Relatedly, use of fruit/sweet/other flavors remained similar overall between 2019 and 2020 (approximately 75-80 % of P30D ENDS users), but the use of these flavors became concentrated in disposable ENDS in 2020 (a 12-fold increase from 4.4 % to 58.4 % of fruit/sweet/other-flavor users). CONCLUSIONS: PATH results show similar trends to other US national surveys in youth ENDS trends. The removal of non-tobacco, non-menthol flavors in pod-based ENDS (while remaining available in disposables) has likely driven youth towards disposable devices, resulting in continued high use of fruit/sweet/other flavors, which are now predominant in users of disposable ENDS. Wave 5.5 is uninformative regarding brand use because common disposable brands were not queried.

Comparison of biomarkers of exposure among US adult smokers, users of electronic nicotine delivery systems, dual users and nonusers, 2018-2019.

The harm caused by cigarette smoking is overwhelmingly due to byproducts of tobacco combustion. Electronic Nicotine Delivery Systems (ENDS) provide nicotine to users without combustion, and may support tobacco harm reduction among cigarette smokers who would not otherwise quit in the near term. Analyses of Wave 5 of the Population Assessment of Tobacco and Health (PATH) Study compared biomarkers of exposure (BOE) levels for nicotine, 3 metals, 2 tobacco-specific nitrosamines and 14 smoking-related volatile organic compounds in 151 exclusive ENDS users, 1341 exclusive cigarette smokers, 115 dual users (cigarettes and ENDS), and 1846 past 30-day nonusers of tobacco, adjusting for demographics. Nicotine exposure in ENDS users and dual users did not significantly differ from smokers. Among ENDS users, 16 of 18 other BOEs were significantly lower than smokers'; 9 BOEs were not significantly different from nonusers. Among dual users smoking < 10 cigarettes/day, 15 of 18 non-nicotine BOEs were significantly lower than smokers', whereas in dual users smoking ≥ 10 cigarettes per day none of the BOEs significantly differed from smokers'. In this representative sample of US adults, exclusive use of ENDS (vs. cigarette smoking) was associated with much lower exposures to many harmful chemicals associated with smoking-related disease. BOE levels in dual users were directly related to their cigarette consumption. These BOE data provide further evidence that ENDS expose users to substantially lower levels of toxicants than combustible cigarettes, confirming their potential for harm reduction.

A New Questionnaire to Assess Respiratory Symptoms (The Respiratory Symptom Experience Scale): Quantitative Psychometric Assessment and Validation Study.

BACKGROUND: Smokers often experience respiratory symptoms (eg, morning cough), and those who stop smoking, including those who do so by switching completely to electronic nicotine delivery systems (ENDS), may experience reductions in symptoms. Existing respiratory symptom questionnaires may not be suitable for studying these changes, as they are intended for patient populations, such as those with chronic obstructive pulmonary disease (COPD). OBJECTIVE: This study aimed to develop a respiratory symptom questionnaire appropriate for current smokers and for assessing changes when smokers stop smoking. METHODS: The Respiratory Symptom Experience Scale (RSES) was derived from existing instruments and subject matter expert input and refined through cognitive debriefing interviews (n=49). Next, for purposes of the quantitative psychometric evaluation, the RSES was administered to smokers (n=202), former smokers (no tobacco use in >6 months; n=200), and switchers (n=208, smokers who switched to ENDS for >6 months), all of whom had smoked for at least 10 years (mean age 33 years). Participants, who averaged 62 (SD 12) years of age, included 28% (173/610) with respiratory allergy symptoms and 17% (104/610) with COPD. Test-retest reliability was assessed by repeat assessment after 1 week in 128 participants. RESULTS: A generalized partial credit model confirmed that the response options were ordered, and a parallel analysis using principal components confirmed that the scale was unidimensional. With allowance for 2 sets of correlated errors between pairs of items, a 1-factor graded response model fit the data. Discrimination parameters were approximately 1 or greater for all items. Scale reliability was 0.80 or higher across a broad range of severity (standardized scores -0.40 to 3.00). Test-retest reliability (absolute intraclass correlation) was good, at 0.89. RSES convergent validity was supported by substantial differences (Cohen d=0.74) between those with and without a diagnosis of respiratory disease (averaging 0.57 points, indicating that differences of this size or smaller represent meaningful differences). RSES scores also strongly differentiated those with and without COPD (d=1.52). Smokers' RSES scores were significantly higher than former smokers' scores (P<.001). Switchers' RSES scores were significantly lower than smokers' scores (P<.001) and no different from former smokers' scores (P=.34). CONCLUSIONS: The RSES fills an important gap in the existing toolkit of respiratory symptom questionnaires; it is a reliable and valid tool to assess respiratory symptoms in adult current and former smokers, including those who have switched to noncombusted nicotine products. This suggests that the scale is sensitive to respiratory symptoms that develop in smokers and to their remission when smokers quit or switch to noncombusted nicotine products intended to reduce the harm of smoking. The findings also suggest that switching from cigarettes to ENDS may improve respiratory health.

Changes in dependence over one year among US adults who smoke cigarettes and switched completely or partially to use of the JUUL-brand electronic nicotine delivery system.

Background: Electronic nicotine delivery systems (ENDS) are substitute sources of nicotine for adults who smoke cigarettes. Understanding changes in dependence as people switch from cigarettes to ENDS is relevant to public health. This study assessed changes in dependence among adults who switched completely or partially (dual users) from cigarettes to JUUL-brand ENDS over 12 months. Methods: US adults who smoke and purchased a JUUL Starter Kit (n = 17,619) completed a baseline assessment and were invited to 1-, 2-, 3-, 6-, 9- and 12-month follow-ups. Dependence on cigarettes at baseline and on JUUL at follow-ups was assessed with the Tobacco Dependence Index (TDI; Range 1-5). Analyses estimated the minimal important difference (MID) for the scale, compared JUUL dependence to baseline cigarette dependence and assessed changes in JUUL dependence over 1-year, including among those using JUUL at all follow-ups. Results: Participants who switched at month 2 had month 1 JUUL TDI scores 0.24 points greater than those who continued smoking (p<0.001); thus MID=0.24. Among both switchers and dual users overall, dependence on JUUL 1 and 12 months later was lower than baseline dependence on cigarettes (ps<0.001); participants who smoked every day showed more consistent and larger reductions. Among participants who persistently used JUUL without smoking, dependence increased 0.01 points per month (p<0.001), but was leveling off over time. Conclusions: Dependence on JUUL was lower than baseline cigarette dependence. Increases in JUUL dependence were small over 12 months of continual JUUL use. These data indicate that ENDS, including JUUL, have lower dependence potential than cigarettes.

Examining reactivity to intensive longitudinal ecological momentary assessment: 12-month prospective study.

PURPOSE: To examine the association between intensive, longitudinal ecological momentary assessment (EMA) and self-reported eating behaviors. METHODS: Secondary analysis of the EMPOWER study-a 12-month observational study that examined the microprocesses of relapse following intentional weight loss using smartphone-administered EMA-was conducted. Participants were asked to complete four types of EMA surveys using a mobile app. For this analysis, only the number of completed random EMA surveys was used. Using linear mixed-effects modeling, we analyzed whether the number of completed random EMA surveys was associated with changes in self-reported dietary restraint, dietary disinhibition, and susceptibility to hunger measured using the Three-Factor Eating Questionnaire (TFEQ). RESULTS: During the 12-month study, 132 participants completed a mean of 1062 random EMA surveys (range: 673-1362). The median time it took for participants to complete random EMA surveys was 20 s and 90% of random EMA surveys were completed within 46 s. The number of completed random EMA surveys was not significantly associated with the TFEQ scores. CONCLUSIONS: Intensive longitudinal EMA did not influence self-reported eating behaviors. The findings suggest that EMA can be used to frequently assess real-world eating behaviors with minimal concern about assessment reactivity. Nonetheless, care must be taken when designing EMA surveys-particularly when using self-reported outcome measures. LEVEL OF EVIDENCE: Level III, prospective observational study.

Population-level counterfactual trend modelling to examine the relationship between smoking prevalence and e-cigarette use among US adults.

BACKGROUND: Studies have suggested that some US adult smokers are switching away from smoking to e-cigarette use. Nationally representative data may reflect such changes in smoking by assessing trends in cigarette and e-cigarette prevalence. The objective of this study is to assess whether and how much smoking prevalence differs from expectations since the introduction of e-cigarettes. METHODS: Annual estimates of smoking and e-cigarette use in US adults varying in age, race/ethnicity, and sex were derived from the National Health Interview Survey. Regression models were fitted to smoking prevalence trends before e-cigarettes became widely available (1999-2009) and trends were extrapolated to 2019 (counterfactual model). Smoking prevalence discrepancies, defined as the difference between projected and actual smoking prevalence from 2010 to 2019, were calculated, to evaluate whether actual smoking prevalence differed from those expected from counterfactual projections. The correlation between smoking discrepancies and e-cigarette use prevalence was investigated. RESULTS: Actual overall smoking prevalence from 2010 to 2019 was significantly lower than counterfactual predictions. The discrepancy was significantly larger as e-cigarette use prevalence increased. In subgroup analyses, discrepancies in smoking prevalence were more pronounced for cohorts with greater e-cigarette use prevalence, namely adults ages 18-34, adult males, and non-Hispanic White adults. CONCLUSION: Population-level data suggest that smoking prevalence has dropped faster than expected, in ways correlated with increased e-cigarette use. This population movement has potential public health implications.

US adult smokers' perceived relative risk on ENDS and its effects on their transitions between cigarettes and ENDS.

BACKGROUND: Perceived risk reduction motivates smokers to switch to electronic nicotine delivery systems (ENDS). This research examines US smokers' relative risk perceptions and their prospective association with various behavioral stages of switching to ENDS. METHODS: Data from the nationally representative, longitudinal Population Assessment of Tobacco and Health (PATH) Adult survey, Waves 1 (2014) through 5 (2019), were analyzed. We assessed the association between the perceived risk of ENDS relative to cigarettes ("less harmful" vs. "equally harmful" or "more harmful") and 1) adoption of ENDS (among never-ENDS-using smokers), 2) complete switching to ENDS (i.e., stopping smoking, among ever-ENDS-using smokers), and 3) avoiding reversion to smoking (among smokers who had switched to ENDS), at the next wave. RESULTS: The proportion of US smokers perceiving ENDS as less harmful than cigarettes continually decreased, reaching 17.4% in Wave 5 (2019). Current smokers with such belief were more likely to adopt ENDS (aOR 1.31; 95% CI 1.15-1.50) and switch completely to ENDS (aOR 2.24; 95% CI 1.89-2.65) in the subsequent wave. Among smokers who had switched within the past year, such beliefs predicted avoidance of resumption of smoking in the next wave (aOR 0.55; 95% CI 0.33-0.93). CONCLUSIONS: Smokers' beliefs about the relative risk of ENDS compared to cigarettes had a strong and consistent association with transitions between smoking and ENDS use. Addressing the growing misperception about ENDS has the potential to contribute to public health by encouraging smokers' switching to ENDS.

Time-varying coefficient cumulative gap time models for intensive longitudinal ecological momentary assessment data with missingness.

Ecological momentary assessment (EMA) studies investigate intensive repeated observations of the current behavior and experiences of subjects in real time. In particular, such studies aim to minimize recall bias and maximize ecological validity, thereby strengthening the investigation and inference of microprocesses that influence behavior in real-world contexts by gathering intensive information on the temporal patterning of behavior of study subjects. Throughout this paper, we focus on the data analysis of an EMA study that examined behavior of intermittent smokers (ITS). Specifically, we sought to explore the pattern of clustered smoking behavior of ITS, or smoking 'bouts', as well as the covariates that predict such smoking behavior. To do this, in this paper we introduce a framework for characterizing the temporal behavior of ITS via the functions of event gap time to distinguish the smoking bouts. We used the time-varying coefficient models for the cumulative log gap time and to characterize the temporal patterns of smoking behavior, while simultaneously adjusting for behavioral covariates, and incorporated the inverse probability weighting into the models to accommodate missing data. Simulation studies showed that irrespective of whether missing by design or missing at random, the model was able to reliably determine prespecified time-varying functional forms of a given covariate coefficient, provided the the within-subject level was small.

Adherence among a cohort taking progestin-only pills prescribed by a healthcare provider: Results of the BENCHMARK study.

OBJECTIVES: To measure adherence over six months of progestin-only pill (POP) use. STUDY DESIGN: Prospective observational cohort study measuring adherence to daily dosing and timing of dose in patients prescribed a POP, with up to six months of follow-up, conducted from January to October 2020. A pharmacy benefit manager identified potential participants with a newly prescribed POP and extended an invitation to participate. We enrolled qualified respondents by telephone, trained them to use an electronic diary to report daily whether they had taken their POP and at what time. We followed participants for up to six months. We calculated adherence to daily pill taking as the proportion of evaluable days in which a participant took a POP, and the proportion of participants reporting ≥85% adherence. We calculated adherence to same time each day as the proportion of doses taken no later than three hours after the previous dose time of day. RESULTS: The user population comprised 199 participants, 154 (77.4%) of whom completed six months of follow-up. The majority (n = 170, 85.4%) were taking norethindrone. Norethindrone users reported POP intake on 22,327 (96.4%) of 23,156 evaluable days, with 155 (91.2%) participants reporting ≥85% adherence; less than half (n = 73, 42.9%) reported 100% adherence. Participants reported adherence to same time each day on 21,698 of 22,157 (97.9%) evaluable days. CONCLUSIONS: Among participants taking a prescribed POP, participants demonstrated high adherence for daily pill taking and the same time of day, though the majority were not 100% adherent. IMPLICATIONS: This study reports data specific to adherence among those taking a progestin-only pill (POP) in the prescription setting. Clinicians who counsel patients about POP use should be aware that majority of patients were not 100% adherent, although most report ≥85% adherence.