Changes in Flavor Preference in a Cohort of Long-Term Electronic Cigarette Users

Rationale: The use of electronic cigarettes (e-cigarettes) has rapidly increased in the United States, and thousands of e-cigarette flavors are available. However, there remains a dearth of evidence on e-cigarette flavor use patterns among older e-cigarette users.Objectives: This longitudinal study examined changes in flavor use patterns in long-term e-cigarette users, assessed self-reported adverse reactions, and evaluated users' anticipated reactions to possible U.S. Food and Drug Administration e-cigarette flavor regulatory scenarios.Methods: The study population was 383 adult participants who completed two online e-cigarette surveys in 2012-2014 (baseline survey) and in 2017-2019 (follow-up survey). In both surveys, participants were asked, "Thinking about your preferred liquid, what is the name of this liquid flavor?" and to list all flavors used in the past 30 days. Flavor preference was classified using the Penn State Three-Step Flavor Classification method. Participants reported adverse events (open-ended description) with the associated flavor. Regulatory scenarios were presented, and participants selected perceived actions from among a list of 15 options.Results: Participants' age averaged 44 ± 12 years; 86% were exclusive e-cigarette users, and 13% reported "poly-use" (i.e., e-cigarette and other tobacco product use). E-cigarette flavor preference migration occurred in all demographic groups: only 36-44% maintained a preference for their original flavor. Preference for tobacco and menthol or mint decreased over time (40% baseline vs. 22% follow-up); preference for fruit remained stable (23% baseline and follow-up), but chocolate/candy or other sweets preference significantly increased (16% baseline vs. 29% follow-up), and other flavors increased slightly. Migration to sweet flavors was more noticeable in younger adults (18-45 yr); exclusive e-cigarette users preferred sweet flavors more commonly than poly-users did (31% vs. 19%). Flavor-associated adverse reactions, mainly respiratory irritations, were reported by 26 (6.9%) participants. Nearly 50% of the participants reported that they would "find a way" to buy their preferred flavor or add flavoring agents themselves if nontobacco flavors were banned.Conclusions: Flavor migration toward sweet flavors occurred in long-term e-cigarette users, a trend most pronounced in younger and exclusive e-cigarette users. The anticipated maintenance of access to flavors despite regulation suggests an element of e-cigarette-related dependence that requires further evaluation. This information could help clinicians understand the health impacts of e-cigarette flavors, develop appropriate strategies for smoking cessation, and inform the U.S. Food and Drug Administration to plan future regulation of e-cigarette flavors.