Liddle 2008.

Methods	Design: RCT Follow‐up: immediate post‐test, 6 & 12 mo (post intervention) Attrition: 45% (immediate post‐test), 46% (6 mo), 39% (12 mo) Unit of randomisation: adolescent
Participants	N of subjects randomised: Int 1:112 Int 2: 112 Total N: 224 N of subjects at 12 mo : Int 1: 39 Int 2: 49 Total N: 88 Age: mean: 15.4 (SD = 1.23) Sex (male): 81% Ethnicity: 72% African American, 18% White, 10% Hispanic Country: USA
Interventions	Number of experimental conditions: 2 Description of Intervention 1: Multi‐Dimensional Family Therapy (MDFT) included a 60 to 90 min weekly session with the family. Therapists work simultaneously in 4 domains depending on the profile of the family (adolescent domain, parent domain, interactional domain, extrafamilial domain). Each session includes a family session and a session with the parent alone and/or a session with the adolescent alone Description of Intervention 2: Cognitive‐Behavioural therapy (CBT), 60 to 90 min weekly session with individual adolescent. Problems are prioritised and a treatment plan is developed. Parents attended the first 2 sessions to support adolescent participation. Next, the aim is to increase coping competence and reduce behaviours that threaten safety, health, and quality of life. Typical strategies include (1) providing information and education; (2) contingency contracting; (3) self‐monitoring; (4) problem‐solving training; (5) communication skills training; (6) identifying cognitive distortions; (7) increasing healthy recreational activities; and (8) providing homework assignments Type of intervention: indicated Focus/target: harm reduction from substance use Fidelity: raters blind to condition; results indicate each condition used techniques in accordance with their model and avoided interventions prescribed in the other treatment Dose: median number of sessions of therapy was 8; no differences between groups in treatment dosage or total time in treatment Duration/frequency: both interventions have 60 to 90 minute weekly sessions Control: not applicable
Outcomes	Length of follow‐up: 12 mo (post intervention) Alcohol outcomes Number of days alcohol used in the previous 30 days
Funding and Declared Conflicts of Interest	Grant from the National Institute on Drug Abuse. Study authors declared no conflicts of interest
Notes	Abbreviations: RCT=randomised controlled trial; N=number; Int=intervention; Ctrl=control; mo=month(s); yr(s)=year(s); NR=not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding of participants and personnel not possible due to the nature of the intervention.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Self‐reported; blinding of participants and personnel not possible due to the nature of the intervention
Incomplete outcome data (attrition bias) All outcomes	High risk	Attrition high, no differential attrition between groups, missing data accommodated by using all available data through full information maximum likelihood estimation and the expectation‐maximisation algorithm
Selective reporting (reporting bias)	Unclear risk	No protocol or clinical trial registry available
Other bias	Low risk	Contamination not described and is unlikely
Recruitment to cluster	Unclear risk	Not applicable
Baseline imbalances	Unclear risk	Not applicable
Loss of clusters	Unclear risk	Not applicable
Incorrect analysis	Unclear risk	Not applicable
Compatability with individually randomised trials (herd effect)	Unclear risk	Not applicable