Layne 2008.

Methods	Randomised trial of a classroom‐based psychoeducation and skills intervention with or without an additional trauma and grief component
Participants	Included (n = 159) War‐exposed adolescents in year 1 to 3 of high school who had undergone significant trauma exposure, reporting significant current distress and functional impairment. Mean age: 15.9 years. Females: 82. 73% had experienced a direct life threat Excluded Students with signs of psychosis, disruptive behavioural or substance abuse problems; those who represented a risk to themselves or others; those unable to participate in groups Setting Ten secondary schools in postwar central Bosnia, 2000 to 2001
Interventions	Trauma and grief‐focused component therapy + psychoeducation and skills intervention (n = 77) Included a trauma and grief‐focused group, which provided trauma and grief processing in addition to psychoeducation and skills intervention. Specific features of the intervention included psychoeducation about reactions to trauma; enhanced coping; trauma and grief processing; building of social support skills; enhanced problem solving; understanding of links between behaviour and trauma; and reappraisal of traumatic expectations. Groups of 6 to 10 participants met for 60 to 90 minutes over 17 to 20 weeks Psychoeducation and skills intervention (n = 82) Classroom intervention that included psychoeducation, skills for managing reminders of trauma and loss and other coping skills taken from selected modules of the trauma and grief component therapy for adolescents. Number of sessions not clear Therapists The 2 therapies were based on different modules of the manualised Trauma and Grief Focused Component Therapy. Treatment was implemented by 16 school counsellors, who received supervision every 2 to 4 weeks
Outcomes	PTSD symptoms Scale: UCLA PTSD Reaction Index (17‐item) Rater: adolescents Depression Scale: Depression Self‐Rating Scale (18‐item) Rater: adolescents When Post therapy and at 4 months
Notes	Loss to follow‐up was greater than 40% for therapy and control groups at 4 months
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Counsellors at each school pulled the names of eligible students out of a box
Allocation concealment (selection bias)	Unclear risk	Not reported
Blinding of participants (performance bias	Unclear risk	Participants were not blinded; both received a psychological therapy, and 1 was classroom‐based
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	All measures were self reported
Incomplete outcome data (attrition bias) All outcomes	High risk	Data were reported for completing participants, and risk was high to follow‐up at both intervals: post therapy 20%; 4 months 38%
Selective reporting (reporting bias)	Low risk	All outcomes appear to have been reported
Other bias	Low risk	No other bias was apparent