Winters 2012.

Methods	Randomised controlled trial
Participants	Number of participants: (315 including adolescents' parents who also received intervention) City and country: Minnesota, USA Type of setting: Urban School setting: Public junior/high school Gender: 48% female, 52% male Mean age: 16.3 years Inclusion criteria: Age 13 to 17, meets diagnostic criteria for 1 or more substance abuse disorders, agrees to participation with parents Exclusion criteria: referred to a treatment programme, meets diagnostic criteria for DSM‐IV substance use dependence, currently in treatment programme, reported acute psychiatric or medical problem/condition
Interventions	Number of adolescents allocated to each group: 136 allocated to experimental group, 56 allocated to control group (123 allocated to adolescent‐parent condition not relevant for this review) Brief intervention: Motivational interviewing style session 1: obtain information about adolescents' substance use and consequences, address willingness to change, look at goals with regards to abstinence, reduction; session 2: some focus on progress to reaching goal, barriers; parenting session: address substance use problem, parent attitudes and behaviours, monitoring and supervision, versus assessment only (control) Dosage: 2 sessions adolescents, 1 session parents Type of delivery: Face‐to‐face (individual) Timing: 1 hour per session, after school hours
Outcomes	Follow‐up at 6 months and 12 months (2014 study) Measures: Adolescent Diagnostic Interview, Timeline Followback, Personal Consequences Scale, Treatment Services Review Primary outcomes: Frequency alcohol use Frequency alcohol binge use Frequency drug use Cannabis dependence symptoms Cannabis abuse symptoms Secondary outcomes: Personal Consequences Scale
Notes	Funding: National Institute on Health (DA017492, AA14866, K02‐DA15347, and P50‐DA027841) Conflict of interest: Information not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random selection by computer random‐number generator
Allocation concealment (selection bias)	High risk	No concealment from investigators, which could introduce selection bias
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding is not possible for the type of intervention
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	It is unclear if the outcome assessment was blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	No difference in 6 months' follow‐up attrition, which was very low. The follow‐up rate for the experimental group was 98.5% and for the control group was 98.2%
Selective reporting (reporting bias)	Low risk	All outcomes were reported
Other bias	Low risk	None reported

DSM‐IV: Diagnostic and Statistical Manual of Mental Disorders, 4th Edition
 FET: further education training