Laboratory Procedures: The aim of the laboratory study is to capture variability in the
TAC-BAC relationship across individuals in a controlled context, featuring manipulations
theorized to confound transdermal measurements of BAC and so ensuring adequate
variability in these factors in the broader dataset. Laboratory alcohol-administration
sessions will be held at one-week intervals, scheduled at study initiation (day 0), study
midpoint (day 7), and study end (day 14).
Alcohol-administration procedures will employ a within (alcohol dose) X between (rate of
consumption) participant design. All participants will consume three doses of alcohol
over the course of the three laboratory sessions, targeting peak blood alcohol
concentration (BAC) levels of .03%, .06%, and .09% respectively. The order of alcohol
doses will be counterbalanced across participants. The exact quantity of alcohol
administered to each participant in order to achieve these target peak BACs will be
calculated based on individualized formulas adjusting for drinking rate, sex, height,
weight, and age (see formulas provided in Watson et al., (1981)). Rate of consumption
will be manipulated between participants, with equal numbers of participants assigned to
consume alcohol at relatively "fast" and "slow" rates. Beverage intake will be monitored
to ensure participant comfort and even consumption across the beverage administration
period. After beverage administration, participants will provide breath alcohol
concentration (BrAC) readings at 10- min intervals.
In addition, during the laboratory procedures, participants will be exposed to
environmental factors that are known to impact readings taken by transdermal sensors.
These manipulations will allow the research team to train the machine learning algorithm
to recognize and model for these environmental effects. These manipulations include: 1)
Environmental alcohol: common household products containing alcohol (e.g., hand
sanitizer, perfume, lotion containing alcohol) will be sprayed or applied in proximity to
the transdermal sensor; 2) Sweating: Participants will be asked to engage in a brief
10-30 minute aerobic exercise while in a seated position (i.e., stationary biking) while
under the supervision of a research assistant. This brief exercise will be designed
simply to yield exertion to the point of sweating and not exertion beyond this point; 3)
Arm Movements: Participants will be asked to engage in isolated body movements (e.g.,
arms and feet) to determine whether device shifting caused by such movements impact
readings taken by transdermal sensors.
Ambulatory Procedures: This arm of the study aims to capture the TAC-BAC relationship
among participants drinking in everyday settings. Ambulatory assessment will take place
over 14 days. During laboratory session 1, prior to beverage administration, participants
will be oriented to ambulatory study procedures. One or more transdermal device will be
worn throughout participation. During orientation, participants will be trained to use
the mobile breathalyzer. To avoid contamination of breathalyzer readings by mouth
alcohol, participants will be instructed to wait 5 minutes after their last sip of
alcohol to provide a reading. Also during this orientation session, participants will
receive training in standard drink reporting (used to validate breathalyzer readings).
During ambulatory assessment, participants will provide breathalyzer readings in response
to both random and user-initiated prompts via their smartphones. On day 14 of the study,
participants will attend a final laboratory session during which they will return study
equipment as well as complete questionnaires asking them to reflect on their experience
using the transdermal sensors and their likelihood to adopt a transdermal sensor
application.
Since initial record creation, the study start date has been updated to conform to
current ICMJE pre-registration requirements. Only participants recruited subsequent, and
not prior to, this updated initiation date are included in reports from the main trial.
