Validation of an E-cigarette Purchase Task in Advanced Generation Device Users.

INTRODUCTION: Behavioral economic purchase tasks are used to estimate the reinforcing value of drugs by asking participants how much they would purchase across a range of increasing prices. We sought to validate such a task for e-cigarettes in experienced users of advanced-generation, tank-style devices. METHODS: Dual users of cigarettes and e-cigarettes (N=54) and exclusive e-cigarette users (N=59) attended one session during which they completed assessments including two versions of the E-Cigarette Purchase Task: one that asked how many puffs of their e-cigarette they would purchase in 24hr at varying prices and one that asked how many milliliters (mLs) of e-liquid they would purchase. We correlated purchase task outcomes with other measures of e-cigarette use. We also compared the tasks across dual and exclusive users. RESULTS: Indices derived from the mLs-based task were more likely to be correlated with self-reported use rates, e-cigarette dependence, and cotinine levels than the puffs-based task. Exclusive users showed greater demand on than dual users only on the mLs version when using an F-Test comparison method; while MANOVA results showed that dual users showed greater demand only on the puffs task. CONCLUSIONS: Results indicate that the mLs version had greater validity than the puffs version in terms of clinical indices. Dual users may still be on a trajectory to fully switching to e-cigarettes; thus, puffs as a measure may be more intuitive, as this measure is shared by cigarettes and e-cigarettes. For exclusive users, the unit they purchase their e-liquid in may be the most relevant unit and better capture their demand for that product. IMPLICATIONS: Behavioral economic purchase tasks have been widely used to understand nicotine use. We have developed two versions of a purchase task for e-cigarette use and compared the two versions in users of advanced generation e-cigarette devices. We found that the milliliters version of the task better reflected use patterns relative to a puffs version, which suggest that participants struggle to place monetary value on a unit of consumption (i.e., puffs). Validated measures of e-cigarette reinforcement will be important as researchers and regulators determine which features of these products contribute to reinforcing efficacy.