Trial Outcomes & Findings for Effect of Waterpipe Size on Smoking Behavior and Exposures (NCT NCT05705375)

Results Overview

The total time spent actively inhaling smoke across all puffs in a WP session, measured in minutes using a puff topography device. Higher values indicate more total inhalation time.

Recruitment status

COMPLETED

Study phase

NA

Target enrollment

40 participants

Primary outcome timeframe

During the exposure (smoking), up to 45 mins

Results posted on

2025-11-05

Participant Flow

Participant milestones

Participant milestones
Measure	Small → Medium → Large Participants first smoke the small WP in Session 1, followed by the medium WP in Session 2, and the large WP in Session 3. Each session lasts 45 minutes and is separated by a 48-hour washout period.	Small → Large → Medium Participants first smoke the small WP, then the large WP, and finally the medium WP, with each 45-minute session separated by a 48-hour washout.	Medium → Large → Small Participants first smoke the medium WP, then the large WP, and finally the small WP, with each 45-minute session separated by a 48-hour washout.	Medium → Small → Large Participants first smoke the medium WP, then the small WP, and finally the large WP, with each 45-minute session separated by a 48-hour washout.	Large → Medium → Small Participants first smoke the large WP, then the medium WP, and finally the small WP, with each 45-minute session separated by a 48-hour washout.	Large → Small → Medium Participants first smoke the large WP, then the small WP, and finally the medium WP, with each 45-minute session separated by a 48-hour washout.
Second Intervention (1 Day) STARTED	3	7	11	6	6	7
Second Intervention (1 Day) COMPLETED	3	7	11	6	6	7
Second Intervention (1 Day) NOT COMPLETED	0	0	0	0	0	0
Washout (48 Hours) STARTED	3	7	11	6	6	7
Washout (48 Hours) COMPLETED	3	7	11	6	6	7
Washout (48 Hours) NOT COMPLETED	0	0	0	0	0	0
Third Intervention (1 Day) STARTED	3	7	11	6	6	7
Third Intervention (1 Day) COMPLETED	3	7	11	6	6	7
Third Intervention (1 Day) NOT COMPLETED	0	0	0	0	0	0
First Intervention (1 Day) STARTED	3	7	11	6	6	7
First Intervention (1 Day) COMPLETED	3	7	11	6	6	7
First Intervention (1 Day) NOT COMPLETED	0	0	0	0	0	0

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

Effect of Waterpipe Size on Smoking Behavior and Exposures

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Waterpipe Regular Smokers n=40 Participants waterpipe regular smokers will be invited for 3 lab visits where they are allocated (random order) to smoke 3 waterpipe different sizes. Waterpipe size: Participants will have 3 lab visits where they are allocated (random order) to smoke a small waterpipe in one visit, smoke a medium waterpipe in a second visit and smoke a large waterpipe in a third visit.
Age, Continuous	24.9 years STANDARD_DEVIATION 3.5 • n=15 Participants
Sex: Female, Male Female	11 Participants n=15 Participants
Sex: Female, Male Male	29 Participants n=15 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=15 Participants
Race (NIH/OMB) Asian	26 Participants n=15 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=15 Participants
Race (NIH/OMB) Black or African American	5 Participants n=15 Participants
Race (NIH/OMB) White	9 Participants n=15 Participants
Race (NIH/OMB) More than one race	0 Participants n=15 Participants
Race (NIH/OMB) Unknown or Not Reported	0 Participants n=15 Participants
Region of Enrollment United States	40 Participants n=15 Participants
Saliva Nicotine	9 ng/mL STANDARD_DEVIATION 3.5 • n=15 Participants
Exhaled Carbon Monoxide	1.2 PPM STANDARD_DEVIATION 0.2 • n=15 Participants

PRIMARY outcome

Timeframe: Immediately after the exposure (smoking)

An 11-item questionnaire assessing participants' subjective experience of smoking waterpipe (WP) tobacco. Each item is scored on a 7-point Likert scale (1 = "not at all" to 7 = "extremely"). For analysis, item scores were averaged across the 11 items to produce a mean WES score for each WP size, with higher scores indicating a more satisfactory smoking experience. The scale captures aspects such as satisfaction, taste, cravings, and sensory enjoyment in the throat and chest.

Outcome measures

Outcome measures
Measure	Medium Waterpipe n=40 Participants waterpipe regular smokers attended 3 lab visits where they are allocated (random order) to smoke 3 waterpipe different sizes.	Large Waterpipe n=40 Participants waterpipe regular smokers attended 3 lab visits where they are allocated (random order) to smoke 3 waterpipe different sizes.	Small Waterpipe n=40 Participants waterpipe regular smokers attended 3 lab visits where they are allocated (random order) to smoke 3 waterpipe different sizes.
Waterpipe Evaluation Scale	4.4 units on a scale Standard Deviation 0.7	4.7 units on a scale Standard Deviation 0.8	4.2 units on a scale Standard Deviation 0.8

PRIMARY outcome

Timeframe: Immediately after the exposure (smoking)

A 9-item questionnaire assessing participants' sensory experience of smoking waterpipe (WP) tobacco. Each item is scored on a 7-point Likert scale (1 = "not at all" to 7 = "extremely"). Item scores were averaged across the 9 items to produce a mean DSQ score for each WP size, with higher scores indicating a more positive sensory experience (e.g., satisfaction, perceived nicotine strength, and puff intensity).

Outcome measures

Outcome measures
Measure	Medium Waterpipe n=40 Participants waterpipe regular smokers attended 3 lab visits where they are allocated (random order) to smoke 3 waterpipe different sizes.	Large Waterpipe n=40 Participants waterpipe regular smokers attended 3 lab visits where they are allocated (random order) to smoke 3 waterpipe different sizes.	Small Waterpipe n=40 Participants waterpipe regular smokers attended 3 lab visits where they are allocated (random order) to smoke 3 waterpipe different sizes.
Duke Sensory Questionnaire	4.0 units on a scale Standard Deviation 0.8	3.8 units on a scale Standard Deviation 0.9	4.4 units on a scale Standard Deviation 0.9

PRIMARY outcome

Timeframe: Immediately after the exposure (smoking)

This is a 3-item scale assessing participants' perception of the harmfulness of waterpipe (WP) tobacco smoking. Each item is scored on a 7-point Likert scale ranging from 1 = "a lot less harmful" to 7 = "a lot more harmful." Item scores were averaged across the 3 items to produce a mean harm perception score for each WP size, with higher scores indicating greater perceived harm.

Outcome measures

Outcome measures
Measure	Medium Waterpipe n=40 Participants waterpipe regular smokers attended 3 lab visits where they are allocated (random order) to smoke 3 waterpipe different sizes.	Large Waterpipe n=40 Participants waterpipe regular smokers attended 3 lab visits where they are allocated (random order) to smoke 3 waterpipe different sizes.	Small Waterpipe n=40 Participants waterpipe regular smokers attended 3 lab visits where they are allocated (random order) to smoke 3 waterpipe different sizes.
Harm Perception Questionnaire	3.7 units on a scale Standard Deviation 0.2	3.8 units on a scale Standard Deviation 0.2	3.5 units on a scale Standard Deviation 0.5

PRIMARY outcome

Timeframe: Immediately after the exposure (smoking)

Population: A small number of participants could not provide adequate saliva nicotine samples due to technical issues encountered during the collection process

How participants' nicotine concentrations change based on the different smoked waterpipe sizes