Monitoring the Rapidly Changing Landscape of E-Cigarettes

E-cigarettes appeared in the United States less than a decade ago as alternatives to conventional cigarettes. These devices gained popularity so rapidly that by 2014, the verb vapeto describe inhaling e-cigarette vaporwas the Oxford English Dictionary's new word of the year (1). Despite their name, e-cigarettes are fundamentally different from conventional cigarettes that burn tobacco and produce smoke. Instead, e-cigarettes are nicotine delivery devices that heat a liquid containing nicotine, solvents, and usually flavorings, producing an aerosol that users inhale (1). The use of e-cigarettes became widespread before their potential health benefits or harms were studied. This occurred because their status as consumer products exempted them from the regulatory oversight required for pharmaceutical nicotine products, such as patches and gum (1). E-cigarettes should be safer than conventional cigarettes, because they expose users to a lower level and smaller number of the harmful components of cigarette smoke, such as carcinogens and oxidant gases, that account for the bulk of tobacco's health risks (1, 2). However, information about the long-term health effects of e-cigarette use is limited, and the net effect of their availability on cigarette smoking initiation and cessation rates remains uncertain (1). The result is a dilemma for physicians, public health practitioners, and policymakers. Meanwhile, as their popularity grew, e-cigarettes themselves rapidly evolved, adding to the challenge. The first products were disposable devices resembling cigarettes, but they soon became larger, reusable devices that users could customize regarding nicotine concentration and flavorings (1). More recently, 2 notable new products emerged. One is a novel vaping device called JUUL (JUUL Labs), which is designed to resemble a computer flash drive and is rechargeable via a USB port (3). Its sleek design, sweet flavors, and social mediafocused marketing seem to have made it more attractive to youths than earlier e-cigarette products. During 2017, JUUL's sales grew rapidly and it captured the largest share of the e-cigarette market (3). The product seems to deliver a higher nicotine dose than previous devices, which may benefit adult smokers seeking to quit, but also might promote nicotine dependence among nonsmoking adolescents and young adults who experiment with it. The second innovation, developed by the tobacco industry, is the heat-not-burn or heated tobacco device (4). Neither a cigarette nor an e-cigarette, this product heats a stick of tobacco, producing an inhalable aerosol, but no smoke. The manufacturers claim that these products reduce health risks compared with cigarette smoking, because they do not burn tobacco but still provide a cigarette flavor. These products currently are not available in the United States, and public awareness of them is minimal (4). However, applications to market them as modified-risk tobacco products are already under review by the U.S. Food and Drug Administration (4). Even less is known about the public health effect of these devices than that of e-cigarettes. With these alternative tobacco products evolving so rapidly, monitoring their use patterns is a high priority for policymakers. Ongoing annual surveys of large, nationally representative samples of adults and adolescents provide the most accurate data. Although these polls have inherent delays in detecting new trends, they provide the best overall snapshot of e-cigarette use at a given time point. The newest information, derived from surveys conducted in 2016, is just appearing. Data from the 2016 National Health Interview Survey (NHIS) were reported in May 2018 (5). The results of the 2016 Behavioral Risk Factor Surveillance System (BRFSS) survey are reported in this issue by Mirbolouk and colleagues (6). Although findings from the 2 surveys generally are consistent, some details differ and each survey contributes some unique data. In both surveys, fewer than 5% of U.S. adults reported using e-cigarettes every day or on some days in 2016. Although both surveys used the same question to measure current use, their weighted prevalence estimates variedfrom 3.2% (95% CI, 2.9% to 3.5%) in the NHIS to 4.5% (CI, 4.4% to 4.6%) in the BRFSS survey (5, 6). Differences in how the data were weighted are a likely explanation for the discrepancy. Technically, the NHIS is nationally representative, whereas the BRFSS survey is designed to represent state populations, and the optimal weighting to generate its national estimates is less certain (7). Therefore, NHIS estimates of national prevalence may be more accurate. Both surveys found consistent patterns of e-cigarette use by age, sex, and race/ethnicity. In both surveys, e-cigarette use was negligible in persons who never smoked conventional cigarettes, higher in former smokers, and highest in current smokers. The 2016 BRFSS survey uniquely provides state-level estimates of e-cigarette use. Overall, the geographic pattern resembles that of conventional cigarette use, as expected, because e-cigarette use is most common among current smokers. The large sample size of the BRFSS survey also provides the statistical power to examine subgroups in finer detail. It detected a higher prevalence of e-cigarette use among lesbian, gay, bisexual, and transgender persons and confirmed NHIS findings from 2014 to 2015 showing that e-cigarette use was more prevalent among adults with chronic health problems than those without comorbid medical conditions (8). Both 2016 surveys provide a clear glimpse of e-cigarette use at a single time point. However, in an evolving landscape, surveillance of changes in use patterns over time is essential and is starting to be carried out. The NHIS has asked about e-cigarettes annually since 2014 and reported a decline in current e-cigarette prevalence in adults between 2014 and 2016 (6). A similar finding was observed in 2016 among adolescents in the National Youth Tobacco Survey, the first decrease in this age group observed after increases since 2011 (9). The PATH (Population Assessment of Tobacco and Health) study is a longitudinal survey of a cohort of adults and adolescents that began in 2013. It can inform us about transitions within individuals, and the adult survey's first 2 waves (2013 to 2015) show a surprising variability in e-cigarette use during 1 year of follow-up (10). The landscape of alternative tobacco products is already complex and likely to become more so going forward. How this will affect the use of new and conventional products by adults and adolescents bears close monitoring. Will the appearance of JUUL counter the recent apparent decline in e-cigarette prevalence in the U.S. population? The answers to that and other critical questions are eagerly awaited.