Forman 1990 (SI).

Methods	Country: USA Site: All 30 secondary schools in south‐eastern metropolitan area. Focus: To evaluate the effectiveness of personal and social coping skills training, with generalization programming in the social environment of the school and home, in preventing substance use in high risk adolescents Design: Cluster RCT (Group 2: change rates).
Participants	Baseline: 327 Age: 14.72 yrs. Gender: Not stated. Ethnicity: W 74%, B 24%, Other 1%. Baseline smoking data: never smoked: school intervention 26%, school and parent intervention 32%, control 27%; used to smoke but quit:  school intervention 14%, School and parent intervention 20%, control 18%.
Interventions	Category: Social competence vs control [social competence and information vs competence control] Programme deliverer: Project Personnel (Master’s degree in a human service discipline and experience working with youth). Intervention: School intervention: student training in coping skills plus training for all professional staff at the school.  Based on Botvin’s (1983) LST. Student training: Ten 2‐hr small group training sessions, conducted once a week. Topics covered behavioural self management, emotional self management, decision‐making and interpersonal communication. Plus substance information by various methods. Two 2‐hr booster sessions one year after initial training. Staff training: half day in‐service training with information on how to encourage and reinforce  coping skills.  School Plus Parent intervention: student training in coping skills, school staff training, and parent training. Same as school intervention, plus parents invited to participate in five weekly, 2‐hr training sessions. Sessions briefed parents on school intervention, behavioural management skills and developed parent support groups. Control: Students attended a structured group that provided attention and focused on self awareness and building a cohesive support group. Students receive the same training schedule as the school intervention. Content adapted from a state school‐based substance abuse programme.
Outcomes	Coping skills acquisition test Personality measures Substance use, knowledge and attitudes using 4 dichotomous self report items: lifetime incidence, monthly recall, weekly recall, 24‐hr recall; Plus frequency of use Archival data Behaviour ratings Results for intervention 2 were split between where parent did attend (SI ‐ P) and where parent did not attend (SI ‐ NP). Follow‐up: Pre and post‐test plus 1 yr.
Notes	Quality of intervention delivery: All sessions recorded and coded by independent raters to establish intended implementation of the interventions.  Intercoder agreement > 90%. "Among the coping skills training groups, half of the sessions covered at least 80% of the planned activities as designed.  The average completion rate of intervention activities across all coping skills sessions was 74%.  Nearly two thirds of the students completed 9 or 10 of the intervention sessions, and 91.9% completed at least 7 sessions.  44% of the students in the School Plus Parent intervention condition had at least one parent participate in the parent training group sessions.  Of the parents who came to the first meeting 66.1% attended all five sessions.  74% of the parents attended at least 4 meetings". Saliva samples collected with a bogus pipeline procedure to enhance the validity of self report results. Statistical quality: Was a power computation performed? Not stated. Was an intention‐to‐treat analysis performed? Not stated. Was a correction for clustering made? Analysis both on individual and cluster basis.  Only individual analysis reported as results similar. Were appropriate statistical methods used? Mean plus SD table; repeated measures multivariate analysis; multiple ANOVA.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Schools "were matched into groups of three on the basis of secondary level (middle vs high school), racial composition, percentage of students receiving free lunch, and school size so that each matched cluster contained schools that were most similar to each other with regard to these characteristics.  Within each cluster, schools were randomly assigned to three treatment conditions". Method of randomisation not stated. Participants within a school selected by staff referral based on observations of high risk characteristics (two or more of: no. of disciplinary incidents, low grades, unexcused absences, drug or alcohol abuse by family member, low self esteem, social withdrawal, experimental substance use). Clusters: School groups. Cluster constraint: Matched groups of three based on secondary school level, racial composition, percentage of students receiving free lunch, and school size. Baseline comparability: never‐smokers: school intervention group 26%, school + parent intervention 32%, control 27%; race (White) School 83%; School + parent 71%, Control 68% (no significances stated).
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Analysis sample = 279 completed the pre‐ and post‐treatment assessment sessions (85.3%). Non‐completing students: 41.7% no longer attended the school, 50% withdrew voluntarily, 8.3% withdrawn due to disruptive behaviour. 201 (72%) completed a booster intervention and follow‐up assessment. Non‐completing students: More than 90% no longer attended the school, 5.1% refused to participate. No differential attrition analysis.
Selective reporting (reporting bias)	Low risk	Purpose of study clearly stated and all expected outcomes provided.