Electronic nicotine delivery systems (ENDS), particularly e-cigarettes, are increasingly prevalent, with their use matching or surpassing conventional cigarettes in certain age groups. Unlike combustible cigarettes, ENDS allow on-demand access to single puffs. Despite the central importance of accurate characterization of ENDS puff behavior in the natural environment, current assessment approaches are quite limited. To overcome critical barriers to progress in the field, we propose to evaluate and deploy an inexpensive instrument that can accurately, objectively, and non-obtrusively track real-time puff behavior across a wide variety of ENDS products without interrupting the natural behavior of the user. The Flexible Robust Instrumentation of ENDS (FRIENDS) monitor employs a miniature non-contact electromagnetic sensor that detects the current flow from the battery through the heater coil, allowing detection of puffs and puff duration regardless of ENDS generation and/or physical form (e.g., cig-alikes, pens, tanks, and pods systems).
In this project we propose recruiting 240 daily ENDS users, sampled for variety of ENDS devices and user characteristics. As new ENDS devices are encountered, they will be bench-tested to determine the best location for FRIENDS attachment, and we will measure the relationship between puff duration and volume. These results will be added to an open-source FRIENDS library. Each participant will vape ad lib with their FRIENDS-enabled ENDS during a video-taped lab visit and for 7 days in their natural environment. Biochemical measures of exposure and a range of self-report data will also be collected. The study will address several critical questions, including: To what extent does self-report reflect accurately capture variability (across people and days) in objective real-world vaping frequency, and how much does objective data from the lab visit improve prediction? To what extent do objective puff measures from FRIENDS outperform self-report measures in predicting nicotine exposure? Finally, what are the objective classes of ENDS use behavior (e.g., predominantly “bingers” [the focus of standard self-report] vs. predominantly “grazers” [a pattern missing from self-report but evident preliminary objective monitoring studies])? How common is each class? Is the ability of self-report to predict real-world vaping frequency and nicotine exposure particularly poor for grazers compared to bingers? The proposed study will provide novel and much-needed information about the nature of ENDS use behavior and has the potential to markedly influence future work. Moreover, the project will curate an extensive, open-source FRIENDS library, providing everything needed to produce and use the FRIENDS monitor with 125+ ENDS. Thus, we will make available to the field an inexpensive and accurate method for assessing puff quantity, duration, and patterning in a wide range of ENDS studies.