An interventional study of webCHAT and Usual Care in Substance-Related Disorders, sponsored by Stanford University. Completed at 2 sites in United States. Open to participants aged 15 Years to 17 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-03-27.
Sponsored by Stanford University · Not applicable, Interventional, and Prevention
The primary goal of this project is to evaluate the efficacy of webCHAT, a single-session web-intervention, on reducing impaired driving among adolescents receiving behind-the-wheel training at driver education programs.
Alcohol and marijuana (AM) are the most commonly used substances among adolescents in the U.S. The consequences of AM use are significantly higher relative to use of either substance alone. This study builds on effective interventions that have demonstrated reductions in alcohol and/or marijuana use and reduced consequences one year later, and proposes to adapt one of those interventions, CHAT, to the web (web-CHAT). The investigators will evaluate the efficacy of web-CHAT among 15.5-17-year-old adolescents (n=150) recruited when teen participants are attending behind-the-wheel training. The study has the potential to promote public welfare by improving adolescent health outcomes and reducing risky driving behaviors that can have substantial monetary and social costs, as well as by providing unique insight into what mediates reduced risky driving attitudes behaviors among those in the intervention. The study is innovative because it is for both youth who are at risk for substance use as well as those who are not, and it is delivered during a teachable moment when adolescents receive driver's education. Finally, this study can provide unique insights about the efficacy of web-CHAT to reduce marijuana initiation, use, and risky driving attitudes in the context of a changing marijuana policy climate. A 3-year study is proposed to test the feasibility of research procedures in a driver education setting and pilot the efficacy of web-CHAT. The investigators will test whether web-CHAT reduces alcohol and/or marijuana initiation or use compared to teens in UC, at three and six-month follow-up.
2,124 studies on the registry are indexed under Substance-Related Disorders; 393 are open to participants now.
This study's enrollment of 198 is above the median of 108 across 1,727 interventional studies indexed under Substance-Related Disorders.
Browse Substance-Related Disorders studies →Stanford University is the lead sponsor of 2,117 studies on the registry; 425 are open to participants now.
Of its 259 completed or terminated interventional studies of FDA-regulated products, 197 (76%) have results posted.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
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.
Behavioral: webCHAT
Existing driving school education
Behavioral: Usual Care
A self-guided, single session web intervention that utilizes a motivational interviewing style to prevent impaired driving
6 hours of driver education
Alcohol and/or Cannabis Use
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)
Time frame: Baseline through 6-month-follow-up
Driving Under the Influence
Number and percentage of participants who drove under the influence of alcohol and/or cannabis in the past 90 days
Time frame: Assessed at 6 month follow-up
Riding With Impaired Driver
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)
Time frame: Baseline through month 6
Perceived Descriptive Norms
Percentage of their peers (0% of their peers-100% of their peers) participants believe have consumed alcohol, cannabis, or both simultaneously in past month
Time frame: 6 month follow-up
| Milestone | webCHAT | Usual Care |
|---|---|---|
| Started | 106 | 92 |
| Completed 3-month survey | 58 | 55 |
| Completed 6-month survey | 64 | 57 |
| Completed | 64 | 57 |
| Not completed | 42 | 35 |
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)
| Participants | webCHAT | Usual Care |
|---|---|---|
| Alcohol | 8 | 2 |
| Cannabis | 7 | 2 |
| Simultaneous Use | 4 | 2 |
Number and percentage of participants who drove under the influence of alcohol and/or cannabis in the past 90 days
| Participants | webCHAT | Usual Care |
|---|---|---|
| Driving Under the Influence | 2 | 3 |
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)
| Participants | webCHAT | Usual Care |
|---|---|---|
| RWID-Alcohol | 9 | 3 |
| RWID-Cannabis | 6 | 0 |
| RWID-Simultaneous | 0 | 0 |
Percentage of their peers (0% of their peers-100% of their peers) participants believe have consumed alcohol, cannabis, or both simultaneously in past month
| Percent of Peers | webCHAT | Usual Care |
|---|---|---|
| Consume Alcohol | 45 ± 21 | 55 ± 22 |
| Consume Cannabis | 36 ± 21 | 48 ± 23 |
| Consume Simultaneously | 26 ± 15 | 36 ± 21 |
Collected over From baseline until the end of follow-up, up to 6 months. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| webCHAT | 0/106 (0%) | 0/106 (0%) | 0/106 (0%) |
| Usual Care | 0/92 (0%) | 0/92 (0%) | 0/92 (0%) |
| Age, Categorical(Participants) | webCHAT | Usual Care | Total |
|---|---|---|---|
| <=18 years | 106 | 92 | 198 |
| Between 18 and 65 years | 0 | 0 | 0 |
| >=65 years | 0 | 0 | 0 |
| Sex/Gender, Customized(Participants) | webCHAT | Usual Care | Total |
|---|---|---|---|
| Gender Identity — Male | 42 | 37 | 79 |
| Gender Identity — Female | 64 | 54 | 118 |
| Gender Identity — Other | 0 | 1 | 1 |
| Race (NIH/OMB)(Participants) | webCHAT | Usual Care | Total |
|---|---|---|---|
| American Indian or Alaska Native | 2 | 0 | 2 |
| Asian | 3 | 3 | 6 |
| Native Hawaiian or Other Pacific Islander | 0 | 1 | 1 |
| Black or African American | 1 | 2 | 3 |
| White | 85 | 73 | 158 |
| More than one race | 13 | 12 | 25 |
| Unknown or Not Reported | 2 | 1 | 3 |
| Ethnicity (NIH/OMB)(Participants) | webCHAT | Usual Care | Total |
|---|---|---|---|
| Hispanic or Latino | 5 | 4 | 9 |
| Not Hispanic or Latino | 101 | 88 | 189 |
| Unknown or Not Reported | 0 | 0 | 0 |
| CRAFFT Screener(Participants) | webCHAT | Usual Care | Total |
|---|---|---|---|
| >=1 | 53 | 46 | 99 |
| <1 | 53 | 46 | 99 |
| Lifetime Substance Use(Participants) | webCHAT | Usual Care | Total |
|---|---|---|---|
| Alcohol | 40 | 31 | 71 |
| Cannabis | 12 | 17 | 29 |
| Simultaneous Cannabis and Alcohol Use | 9 | 10 | 19 |
| No Lifetime History | 45 | 34 | 79 |
| Lifetime History of Riding with Impaired Driver(Participants) | webCHAT | Usual Care | Total |
|---|---|---|---|
| Rode with Impaired Driver | 33 | 34 | 67 |
| Did Not Ride with Impaired Driver | 73 | 58 | 131 |
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This study is completed, as verified in Mar 2026. You cannot join it, but the record below documents what was studied.
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