Jaycox 1994.

Methods	Design: cluster‐RCT Conducted by the team who developed the intervention: yes
Participants	Description: targeted Cut‐point for inclusion for indicated studies: ≥ 0.50 on a composite score based on the z score of the CDI and the Child’s Perception Questionnaire of parental conflict. Those scoring below this composite score, however, were included in the trial subject to availability and space in the groups. What risk was basis of inclusion for selected studies: child’s perception of parental conflict Diagnostic interview to exclude those with current or previous depression: not undertaken. Unclear whether those with current and/or past episodes of depression were excluded. Baseline severity of depression: CDI: 9.5 (sub‐threshold)   Mean age: 11.4 Age range: 10 to 13 Percentage male: 53.8% Setting: school   State what psychiatric diagnoses were excluded: exclusion criteria not specified Suicide risk excluded: exclusion criteria not specified Parents with history of schizophrenia/bipolar disorder excluded: exclusion criteria not specified   Country: USA
Interventions	Broad category: CBT (for further information on intervention components, see Table 3) Manualised: yes Online: no Name of programme: Penn Prevention Program (Penn Resiliency Program) Number of sessions: 12 sessions Length of sessions: 90 minutes Intensity (total number of hours): 18 hours Duration of treatment period: 12 weeks Group size: 10 to 12 Delivered by: students Fidelity: not assessed Type of comparison: WL
Outcomes	Diagnosis: established from CDI of ≥ 15 Name of self‐report depression measure: CDI, RADS and a composite measure Name of clinical report depression measure: N/A Name of anxiety measure: N/A Name of general functioning measure: N/A Assessment points: post‐intervention and 12 weeks (short‐term)
Notes	Author contacted for methodological detail: yes (provided) Author contacted for treatment manual: yes (not provided) Author contacted for outcome data: no There were 8 clusters and we assumed 4 in each
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Correspondence with study authors revealed that the randomisation sequence was generated by pulling envelopes were picked out of a hat
Allocation concealment (selection bias)	Low risk	Correspondence with study authors revealed that the person generating the allocation sequence could not see what was written in each envelope
Blinding (performance bias and detection bias) Subjects	High risk	The nature of the trial suggests it is unlikely participants could have remained blind to the fact they were allocated to wait‐list control group. However, without access to the participant information sheets and PLS, level of blinding cannot be ascertained.
Blinding (performance bias and detection bias) Assessors	Unclear risk	All outcomes self‐reported. Assessor blinding therefore not applicable.
Incomplete outcome data (attrition bias) All outcomes	High risk	Proportion of participants with incomplete post‐intervention self‐reported depression scores: 15.38% Means and SDs used in meta‐analysis based on what data: observed cases Intention‐to‐treat analyses: unclear if undertaken
Selective reporting (reporting bias)	High risk	Protocol not available. However, the trial commenced with 3 separate intervention groups that were subsequently combined in a post‐hoc manner as there were no differences between them in terms of main outcomes at post‐test.
Other bias	High risk	Trial conducted by those who developed the intervention
Implementation integrity	Unclear risk	Implementation integrity assessed: unclear if assessed Implementation integrity adequate: N/A Implementation integrity reported: N/A