Trial Outcomes & Findings for Cigarette Smoking in Smokers With and Without Schizophrenia (NCT NCT04001114)

Last Updated: 2024-09-26

Results Overview

The concentration (ppm) of carbon monoxide (CO) in breath is measured by exhalation into a CO breathalyzer at the end of the 8-hour Ad Libitum Smoking Session. Only very-low-nicotine-content (virtually nicotine-free) cigarettes were consumed in this session.

Recruitment status

COMPLETED

Study phase

Target enrollment

31 participants

Primary outcome timeframe

One day (in the Ad Libitum Smoking Session), over an 8-hour time frame.

Results posted on

2024-09-26

Participant Flow

Participant milestones

Participant milestones
Measure	Smokers With Schizophrenia This is a diagnostic group, defined independently from this study. Sampling Research Cigarettes: Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.	Smokers Without Schizophrenia This is a diagnostic group (i.e., no diagnosis of schizophrenia), defined independently from this study. Sampling Research Cigarettes: Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.
Overall Study STARTED	18	13
Overall Study COMPLETED	17	9
Overall Study NOT COMPLETED	1	4

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

Cigarette Smoking in Smokers With and Without Schizophrenia

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Smokers With Schizophrenia n=18 Participants This is a diagnostic group, defined independently from this study. Sampling Research Cigarettes: Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.	Smokers Without Schizophrenia n=13 Participants This is a diagnostic group (i.e., no diagnosis of schizophrenia), defined independently from this study. Sampling Research Cigarettes: Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.	Total n=31 Participants Total of all reporting groups
Age, Continuous	37.1 years STANDARD_DEVIATION 11.9 • n=5 Participants	48.3 years STANDARD_DEVIATION 7.5 • n=7 Participants	43.7 years STANDARD_DEVIATION 11.1 • n=5 Participants
Sex: Female, Male Female	7 Participants n=5 Participants	7 Participants n=7 Participants	14 Participants n=5 Participants
Sex: Female, Male Male	11 Participants n=5 Participants	6 Participants n=7 Participants	17 Participants n=5 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) Asian	2 Participants n=5 Participants	0 Participants n=7 Participants	2 Participants n=5 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) Black or African American	10 Participants n=5 Participants	10 Participants n=7 Participants	20 Participants n=5 Participants
Race (NIH/OMB) White	6 Participants n=5 Participants	2 Participants n=7 Participants	8 Participants n=5 Participants
Race (NIH/OMB) More than one race	0 Participants n=5 Participants	1 Participants n=7 Participants	1 Participants n=5 Participants
Race (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Region of Enrollment United States	18 participants n=5 Participants	13 participants n=7 Participants	31 participants n=5 Participants

PRIMARY outcome

Timeframe: One day (in the Ad Libitum Smoking Session), over an 8-hour time frame.

Population: One smoker with schizophrenia and one smoker without schizophrenia did not complete the study session in which this measurement was obtained but completed all other study sessions.

Outcome measures

Outcome measures
Measure	Smokers With Schizophrenia n=16 Participants This is a diagnostic group, defined independently from this study. Sampling Research Cigarettes: Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.	Smokers Without Schizophrenia n=8 Participants This is a diagnostic group (i.e., no diagnosis of schizophrenia), defined independently from this study. Sampling Research Cigarettes: Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.
End-of-session Carbon Monoxide	62.7 parts per million (ppm) Standard Deviation 41.7	43.0 parts per million (ppm) Standard Deviation 23.3

PRIMARY outcome

Timeframe: One day (in the Cigarette Discrimination Session), over a 6-hour time frame.

Population: One smoker with schizophrenia did not complete the study session in which this measurement was obtained, but completed the rest of the study.

Participants sample 4 cigarettes of type A and 4 cigarettes of type B in a double-blind manner and indicate for each cigarette if they think it is of type A or B. Two reference trials with cigarette type unblinded will be performed before the first and fifth sample cigarette. For each sampled cigarette, the score is either 1 (correct) or 0 (incorrect). Discrimination accuracy is calculated by averaging the eight scores for each participant.

Outcome measures

Outcome measures
Measure	Smokers With Schizophrenia n=16 Participants This is a diagnostic group, defined independently from this study. Sampling Research Cigarettes: Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.	Smokers Without Schizophrenia n=9 Participants This is a diagnostic group (i.e., no diagnosis of schizophrenia), defined independently from this study. Sampling Research Cigarettes: Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.
Cigarette Discrimination Accuracy	65.6 percentage of choices that were correct Standard Deviation 31.8	81.9 percentage of choices that were correct Standard Deviation 11.0

SECONDARY outcome

Timeframe: One day (in the Ad Libitum Smoking Session), over an 8-hour time frame.

Population: One smoker with schizophrenia and one smoker without schizophrenia did not complete the study session in which this measurement was obtained but completed the rest of the study.

In the Ad Libitum Smoking Session, participants can smoke as many research cigarettes (all very-low-nicotine-content) as they wish. The propensity to maintain smoking despite the absence of nicotine was quantified by subtracting the number of cigarettes smoked in the last two hours from that in the first two hours of the session. Smaller difference values indicate that smoking was upheld by very-low-nicotine-content cigarettes.

Outcome measures

Outcome measures
Measure	Smokers With Schizophrenia n=16 Participants This is a diagnostic group, defined independently from this study. Sampling Research Cigarettes: Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.	Smokers Without Schizophrenia n=8 Participants This is a diagnostic group (i.e., no diagnosis of schizophrenia), defined independently from this study. Sampling Research Cigarettes: Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.
Change in the Number of Research Cigarettes Smoked	1.75 difference in cigarettes smoked Standard Deviation 4.30	1.50 difference in cigarettes smoked Standard Deviation 0.93

SECONDARY outcome

Timeframe: One day (in the Cigarette Discrimination Session), over a 6-hour time frame.

Population: One smoker with schizophrenia and one smoker without schizophrenia did not complete the study session in which this measurement was obtained. One additional smoker with schizophrenia did not complete the subjective state measurements but completed all other aspects of the session.

The measure is derived by transforming scores on the Minnesota Nicotine Withdrawal Scale (where higher values signify more withdrawal), the Affect-based Withdrawal Scale (higher values signify a worse emotional state), Questionnaire for Smoking Urges (higher values indicate more craving), and modified Cigarette Evaluation Questionnaire (mCEQ, higher values indicate greater subjective effects of smoking on mood, hunger, physiology) into standard z-scores, thus giving each scale a mean of 0 and standard deviation of 1. Withdrawal and craving scores were re-poled (inversing the sign), and scales were averaged for each subject. The resulting composite quantified the subjective state response to cigarette smoking, larger values indicating less withdrawal, less craving, and larger effects on the mCEQ. The difference therein between the research cigarettes containing nicotine and those containing almost no nicotine quantified the subjective state response to nicotine.

Outcome measures

Outcome measures
Measure	Smokers With Schizophrenia n=15 Participants This is a diagnostic group, defined independently from this study. Sampling Research Cigarettes: Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.	Smokers Without Schizophrenia n=9 Participants This is a diagnostic group (i.e., no diagnosis of schizophrenia), defined independently from this study. Sampling Research Cigarettes: Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.
Difference in Subjective State Composite Score	0.13 difference in z-score Standard Deviation 0.26	0.039 difference in z-score Standard Deviation 0.15

Adverse Events

Smokers With Schizophrenia

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Smokers Without Schizophrenia

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Britta Hahn, Ph.D.

University of Maryland

Phone: 410-402-6112

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place