Trial Outcomes & Findings for Assessing the Effect of Nicotine Reduction on ENDS User's Addiction and Exposures (NCT NCT05205382)

In total, 116 participants have completed both lab sessions. In our results, we reported data from 105 participants, as we excluded data from 11 participants for missing information due to machine errors or other errors (i.g., the topography machine did not work).

Assessing the Effect of Nicotine Reduction on ENDS User's Addiction and Exposures

Change in plasma nicotine level. The plasma nicotine boost was calculated by subtracting the preplasma nicotine value from the postplasma value.

Measurement of puffing behavior in total puffing time

Measurement of puffing behavior in average puffing duration

Measurement of puffing behavior; mean of the number of puffs taken during the ad-libitum smoking session

Measurement of puffing behavior; mean volume of puffs inhaled during the ad-libitum smoking session

This aim elucidates how compensatory puffing behavior in response to NR affects exposure to pulmonary toxicants. The analytical assessments were conducted at the AUB Aerosol Research Laboratory (ARL) using the Aerosol Lab Vaping Instrument (ALVIN). The ALVIN is programmed to playback participants' puffing behavior recorded during their two sessions (for both partial and total nicotine reduction studies) to generate and sample the e-cigarette aerosol for analysis. The ARL is equipped with gas chromatographs with a flame ionization detector and a mass spectrometer (GC-FID, GC-MS), as well as and High-performance liquid chromatography Mass Spectrometry (HPLC-MS) for aldehydes analysis. ARL optimized analytical methods have been used in several NIH-funded studies of ENDS nicotine and aldehydes emissions.

This aim elucidates how compensatory puffing behavior in response to NR affects exposure to pulmonary toxicants. The analytical assessments were conducted at the AUB Aerosol Research Laboratory (ARL) using the Aerosol Lab Vaping Instrument (ALVIN). The ALVIN is programmed to playback participants' puffing behavior recorded during their two sessions (for both partial and total nicotine reduction studies) to generate and sample the e-cigarette aerosol for analysis. The ARL is equipped with gas chromatographs with a flame ionization detector and a mass spectrometer (GC-FID, GC-MS), as well as and High-performance liquid chromatography Mass Spectrometry (HPLC-MS) for aldehydes analysis. ARL optimized analytical methods have been used in several NIH-funded studies of ENDS nicotine and aldehydes emissions.

LFTs (i.e., lung volume testing, airway resistance, specific airway conductance) will be measured before and immediately after ENDS use. According to 2019 American Thoracic Society and European Respiratory Society recommendation simple spirometry (e.g., change in FVC and FEV1) will be performed. Note: This outcome is not involved in multiple assessments since all the values will appear on the spirometry at the same time.

LFTs (i.e., lung volume testing, airway resistance, specific airway conductance) will be measured before and immediately after ENDS use. According to 2019 American Thoracic Society and European Respiratory Society recommendation simple spirometry (e.g., % predicted value pred (FVC), FEV1 % pred FEV1/FVC, % pred) will be performed. Note: This outcome is not involved in multiple assessments since all the values will appear on the spirometry at the same time.

Nicotine withdrawal symptoms were measured using the Minnesota Nicotine Withdrawal Scale (MNWS) before and after each vaping session. MNWS evaluates 11 withdrawal-related symptoms, including depressed mood, irritability, restlessness, hunger, and difficulty concentrating, using scale from "0" (not at all) to "100" (extremely). For each session and condition, change scores were calculated by subtracting pre-session from post-session scores for each individual item

The Tiffany-Drobes Questionnaire of Smoking Urges-Brief (QSU-Brief) is a 10-item self-report measure of cigarette craving and urge to smoke. It consists of two subscales representing distinct dimensions of craving: Factor 1 (Desire and Intention to Smoke): assesses desire, intention, and anticipation of pleasure associated with smoking. Factor 2 (Anticipation of Relief from Negative Affect and Withdrawal): assesses expectations that smoking will relieve withdrawal symptoms or negative affect. Each item is rated on a 7-point Likert scale ranging from 1 = strongly disagree to 7 = strongly agree. Subscale scores were calculated by averaging the items within each factor. Higher scores on either factor indicate greater smoking urge or craving, representing a worse outcome, whereas lower scores indicate lower craving or urge to smoke, representing a better outcome. Pre- to post-session change scores were calculated as pre-session score minus post-session score for each factor.

This scale will assess participants sensory experience of the inhaled product. The scale has nine items. All items will be scored on a 7-point Likert scale anchored at the extremes (1= not at all; 7=extremely).

Modified Cigarette Evaluation Questionnaire (mCEQ) is used to assess subjective effects associated with ENDS use. The 11-item questionnaire evaluates satisfaction, psychological reward, enjoyment of respiratory tract sensations, craving reduction and aversion. Individual item scores were reported (not subscales). Each item was rated using 7-point Likert scale; 1 = not at all to 7 = extremely. For all items, higher scores indicate greater endorsement of the measured subjective experience, while lower scores indicate less endorsement of that experience. The interpretation depends on the construct being measured: For items assessing satisfaction, enjoyment, psychological reward, sensory experiences, and craving reduction, higher scores indicate greater product reinforcement or abuse liability. For items assessing aversion, higher scores indicate greater unpleasant effects or product aversiveness.

This scale contains 10-item questions to assess users' pleasure and enjoyment using the validated Visual Analog Scale (VAS) post ENDS use sessions. The scale includes items to assess user's desire, pleasure, satisfaction, future use, and other information rated on an analog scale (0 not at all to 100 extremely).

Change in heart rate, measured in beats per minute (bpm).

Change in systolic blood pressure, measured in mm/hg.

Change in diastolic blood pressure, measured in mm/hg.