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 24 hours at varying prices and one that asked how many 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 multivariate analysis of variance (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 mLs version of the task better-reflected use patterns relative to a puffs version, which suggests that participants struggle to place monetary value on a unit of consumption (ie, puffs). Validated measures of e-cigarette reinforcement will be important as researchers and regulators determine which features of these products contribute to reinforcing efficacy.