Trial Outcomes & Findings for Preventing Impaired Driving Among Adolescents (NCT NCT04959461)

Last Updated: 2026-03-27

Results Overview

Total number of participants who self-reported an increased frequency of using the specified substance or substance combination in the past 3 months at 3- and/or 6-month-follow-up when compared to baseline, as denoted by a binary variable (1 = increased frequency; 0 = maintained or decreased frequency)

Recruitment status

COMPLETED

Study phase

Target enrollment

198 participants

Primary outcome timeframe

Baseline through 6-month-follow-up

Results posted on

2026-03-27

Participant Flow

Participant milestones

Participant milestones
Measure	webCHAT Single session 20-40minute self-guided web program that discusses promotes healthy decision making around driving and discusses the risks of alcohol and cannabis-influenced driving.	Usual Care Existing driving school education
Overall Study STARTED	106	92
Overall Study Completed 3-month survey	58	55
Overall Study Completed 6-month survey	64	57
Overall Study COMPLETED	64	57
Overall Study NOT COMPLETED	42	35

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

Preventing Impaired Driving Among Adolescents

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	webCHAT n=106 Participants Single session 20-40minute self-guided web program that discusses promotes healthy decision making around driving and discusses the risks of alcohol and cannabis-influenced driving.	Usual Care n=92 Participants Existing driving school education	Total n=198 Participants Total of all reporting groups
Age, Categorical <=18 years	106 Participants n=56 Participants	92 Participants n=62 Participants	198 Participants n=123 Participants
Age, Categorical Between 18 and 65 years	0 Participants n=56 Participants	0 Participants n=62 Participants	0 Participants n=123 Participants
Age, Categorical >=65 years	0 Participants n=56 Participants	0 Participants n=62 Participants	0 Participants n=123 Participants
Sex/Gender, Customized Gender Identity · Male	42 Participants n=56 Participants	37 Participants n=62 Participants	79 Participants n=123 Participants
Sex/Gender, Customized Gender Identity · Female	64 Participants n=56 Participants	54 Participants n=62 Participants	118 Participants n=123 Participants
Sex/Gender, Customized Gender Identity · Other	0 Participants n=56 Participants	1 Participants n=62 Participants	1 Participants n=123 Participants
Race (NIH/OMB) American Indian or Alaska Native	2 Participants n=56 Participants	0 Participants n=62 Participants	2 Participants n=123 Participants
Race (NIH/OMB) Asian	3 Participants n=56 Participants	3 Participants n=62 Participants	6 Participants n=123 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=56 Participants	1 Participants n=62 Participants	1 Participants n=123 Participants
Race (NIH/OMB) Black or African American	1 Participants n=56 Participants	2 Participants n=62 Participants	3 Participants n=123 Participants
Race (NIH/OMB) White	85 Participants n=56 Participants	73 Participants n=62 Participants	158 Participants n=123 Participants
Race (NIH/OMB) More than one race	13 Participants n=56 Participants	12 Participants n=62 Participants	25 Participants n=123 Participants
Race (NIH/OMB) Unknown or Not Reported	2 Participants n=56 Participants	1 Participants n=62 Participants	3 Participants n=123 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	5 Participants n=56 Participants	4 Participants n=62 Participants	9 Participants n=123 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	101 Participants n=56 Participants	88 Participants n=62 Participants	189 Participants n=123 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	0 Participants n=56 Participants	0 Participants n=62 Participants	0 Participants n=123 Participants
CRAFFT Screener >=1	53 Participants n=56 Participants	46 Participants n=62 Participants	99 Participants n=123 Participants
CRAFFT Screener <1	53 Participants n=56 Participants	46 Participants n=62 Participants	99 Participants n=123 Participants
Lifetime Substance Use Alcohol	40 Participants n=56 Participants	31 Participants n=62 Participants	71 Participants n=123 Participants
Lifetime Substance Use Cannabis	12 Participants n=56 Participants	17 Participants n=62 Participants	29 Participants n=123 Participants
Lifetime Substance Use Simultaneous Cannabis and Alcohol Use	9 Participants n=56 Participants	10 Participants n=62 Participants	19 Participants n=123 Participants
Lifetime Substance Use No Lifetime History	45 Participants n=56 Participants	34 Participants n=62 Participants	79 Participants n=123 Participants
Lifetime History of Riding with Impaired Driver Rode with Impaired Driver	33 Participants n=56 Participants	34 Participants n=62 Participants	67 Participants n=123 Participants
Lifetime History of Riding with Impaired Driver Did Not Ride with Impaired Driver	73 Participants n=56 Participants	58 Participants n=62 Participants	131 Participants n=123 Participants

PRIMARY outcome

Timeframe: Baseline through 6-month-follow-up

Outcome measures

Outcome measures
Measure	webCHAT n=64 Participants Single session 20-40minute self-guided web program that discusses promotes healthy decision making around driving and discusses the risks of alcohol and cannabis-influenced driving.	Usual Care n=57 Participants Existing driving school education
Alcohol and/or Cannabis Use Simultaneous Use	4 Participants	2 Participants
Alcohol and/or Cannabis Use Alcohol	8 Participants	2 Participants
Alcohol and/or Cannabis Use Cannabis	7 Participants	2 Participants

SECONDARY outcome

Timeframe: Assessed at 6 month follow-up

Number and percentage of participants who drove under the influence of alcohol and/or cannabis in the past 90 days

Outcome measures

Outcome measures
Measure	webCHAT n=64 Participants Single session 20-40minute self-guided web program that discusses promotes healthy decision making around driving and discusses the risks of alcohol and cannabis-influenced driving.	Usual Care n=57 Participants Existing driving school education
Driving Under the Influence	2 Participants	3 Participants

SECONDARY outcome

Timeframe: Baseline through month 6

Total number of participants who self-reported an increased frequency of riding with an impaired driver (RWID) who had consumed the specified substance or combination of substances in the past 3 months at 3- and/or 6-month-follow-up when compared to baseline as indicated by a binary (1 = increased frequency; 0 = maintained or reduced frequency)

Outcome measures

Outcome measures
Measure	webCHAT n=64 Participants Single session 20-40minute self-guided web program that discusses promotes healthy decision making around driving and discusses the risks of alcohol and cannabis-influenced driving.	Usual Care n=57 Participants Existing driving school education
Riding With Impaired Driver RWID-Alcohol	9 Participants	3 Participants
Riding With Impaired Driver RWID-Cannabis	6 Participants	0 Participants
Riding With Impaired Driver RWID-Simultaneous	0 Participants	0 Participants

SECONDARY outcome

Timeframe: 6 month follow-up

Percentage of their peers (0% of their peers-100% of their peers) participants believe have consumed alcohol, cannabis, or both simultaneously in past month

Outcome measures

Outcome measures
Measure	webCHAT n=64 Participants Single session 20-40minute self-guided web program that discusses promotes healthy decision making around driving and discusses the risks of alcohol and cannabis-influenced driving.	Usual Care n=57 Participants Existing driving school education
Perceived Descriptive Norms Consume Alcohol	45 Percent of Peers Standard Deviation 21	55 Percent of Peers Standard Deviation 22
Perceived Descriptive Norms Consume Cannabis	36 Percent of Peers Standard Deviation 21	48 Percent of Peers Standard Deviation 23
Perceived Descriptive Norms Consume Simultaneously	26 Percent of Peers Standard Deviation 15	36 Percent of Peers Standard Deviation 21

Adverse Events

webCHAT

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Usual Care

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

Dr. Karen Osilla (PI)

Stanford University School of Medicine

Phone: (650) 721-7091

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place